Introduction

Social visibility of same-gender parented families has significantly increased in the last few years across Europe and the USA. However, negative beliefs about these families are still prevalent and widespread (Clarke, 2001; Costa et al., 2014). Heterosexual individuals who have internalized negative beliefs about same-gender relationships, namely, the idea that these are deviant compared to different-gender relationships, express them in the form of sexual prejudice (Herek, 2009). The belief that lesbians and gay men are unable to have healthy and stable relationships and consequently to raise well-adjusted children is a reflection of sexual prejudice. Thus, negative attitudes toward same-gender marriage and same-gender parenting fuel manifestations of sexual prejudice and may justify preexisting negative feelings and beliefs regarding sexual minorities.

Attitudes Toward Gay Men and Lesbians, Same-Gender Marriage, and Same-Gender Parenting

Literature has revealed important variables that influence attitudes toward lesbians and gay men, namely, sociodemographic and psychological characteristics (age, gender, education, religiosity, political orientation, and cultural differences), and etiological beliefs about homosexuality (Brown & Henriquez, 2008; Costa et al., 2014; Haider-Markel & Joslyn, 2008; Whitley & Ægisdóttir, 2000; Whitley & Lee, 2000). These factors have also been shown to predict attitudes toward same-gender marriage (Anderssen, 2002; Brumbaugh, Sanchez, Nock, & Wright, 2008; Ellison, Acevedo, & Ramos-Wada, 2011; Finlay & Walther, 2003; Olson, Cadge, & Harrison, 2006) and same-gender parenting (Costa, Pereira, & Leal, 2015; Webb & Chonody, 2014).

Among these variables, gender and gender role beliefs are suggested to be strong predictors of sexual prejudice (Brown & Henriquez, 2008). Literature has shown that heterosexual men tend to hold more negative attitudes toward lesbians and gay men than women (Costa et al., 2014). Moreover, these negative perceptions are stronger toward gay men than toward lesbians (Costa & Davies, 2012; Moskowitz, Rieger, & Roloff, 2010), indicating that this gender difference is engrained in gender role beliefs. Religiosity and attendance of religious services are also important predictors of negative attitudes toward gay men and lesbians, regardless of specific religion or denomination (Brown & Henriquez, 2008; Whitley, 2008). Political orientation is also linked to negative attitudes, namely, right-wing inclination and conservatism (Whitley & Ægisdóttir, 2000; Whitley & Lee, 2000), which is also associated with religiosity and other traditional beliefs (Costa et al., 2014).

Likewise, individual beliefs about the etiology of homosexuality are associated with negative attitudes against gay men and lesbians. Heterosexual individuals who believe that homosexuality is biologically determined are more likely to hold lower levels of sexual prejudice (Hans, Kersey, & Kimberly, 2012). Conversely, heterosexual individuals who believe that homosexuality is a lifestyle choice or socially constructed have higher levels of sexual prejudice (Sheldon, Pfeffer, Jayaratne, Feldbaum, & Petty, 2007). Furthermore, some of the abovementioned sociodemographic variables such as age, gender, and religiosity have been shown to be partially mediated by etiological beliefs, which discloses some of the foundations for negative attitudes toward gay men and lesbians as parents (Frías-Navarro, Monterde-i-Bort, Pascual-Soler, & Badenes-Ribera, 2015).

Beliefs about the etiology of homosexuality also influence attitudes toward same-gender marriage (Webb & Chonody, 2014), in that the belief that there is a biological cause for homosexuality is linked to positive attitudes toward same-gender marriage (Haslam & Levy, 2006; Malcomnson, Christopher, Franzen, & Keyes, 2006). Men tend to hold higher levels of sexual prejudice and stronger beliefs of a social etiology of homosexuality (Costa et al., 2014; Frías-Navarro et al., 2015).

Although numerous studies have uncovered sociodemographic and psychological predictors of attitudes toward lesbians and gay men and same-gender marriage, literature about heterosexuals’ attitudes toward same-gender parenting is still scarce (Costa et al., 2014). Likewise, the relationship between attitudes toward same-gender marriage and parenting has been insufficiently explored (Webb & Chonody, 2014). However, Schoephoerster and Aamlid’s study (2016) has suggested that individuals who support same-gender marriage tend to be more supportive of same-gender parenting when compared to individuals who have negative attitudes regarding same-gender marriage.

Despite the scientific consensus that being raised by same-gender parents does not have harmful effects on the child’s well-being (Crowl, Ahn, & Baker, 2008; Fedewa, Black, & Ahn, 2015), negative beliefs about same-gender parented families seem to be highly prevalent (Avery et al., 2007; Costa et al., 2014), In the USA and Australia, significant changes in heterosexuals’ perceptions of same-gender parented families have been occurring (Brumbaugh et al., 2008; Crawford & Solliday, 1996; Fraser, Fish, & MacKenzie, 1995), although literature has shown that individuals are still more reluctant to agree with giving child custody to a same-gender couple, particularly to a male same-gender couple, than to a different-gender couple (Averett & Hegde, 2012; Camilleri & Ryan, 2006; Choi, Thul, Berenhaut, Suerken, & Norris, 2006). Moreover, concerns over society’s acceptance of these families, as well as fears over children’s well-being due to potential victimization or harassment experiences at school, still persist (Bliss & Harris, 1999; Crawford, McLeod, Zamboni, & Jordan, 1999; King & Black, 1999).

European Context

According to recent studies, attitudes toward same-gender marriage and same-gender parenting are highly diverse among European Union member states (Commissioner for Human Rights, 2011). Individuals from the Netherlands and Sweden have shown the highest levels of acceptance of same-gender marriage (82 and 71%, respectively) and same-gender parenting (69 and 51%, respectively). Another study from the UK (Populus, 2009, as cited in Webb & Chonody, 2014) has shown that 61% of their sample supported same-gender marriage and 49% supported same-gender adoption. Overall, it is suggested that the majority of people are more supportive of same-gender marriage than of same-gender parented families (Hollekim, Slaatten, & Anderssen, 2012).

Portugal is no exception since 29% of individuals reported being favorable to same-gender marriage and only 19% to same-gender parenting (Commissioner for Human Rights, 2011). In fact, a transcultural study with 32 European countries about several attitudinal patterns revealed that Portugal was among the least supportive of homosexuality, clustered with mostly former Soviet states (Lottes & Alkula, 2011). Furthermore, a recent study examining social attitudes toward same-gender adoption among 28 European countries concluded that Portuguese individuals’ attitudes were below the scale’s mid-point and scoring between Russia and Romania (Takács, Szalma, & Bartus, 2016). These findings seem to be misaligned with Portugal’s progressive legislation regarding the recognition of same-gender relationships. Despite much controversy and several failed parliamentary attempts to allow same-gender couples to marry and to have children through adoption or assisted reproduction, same-gender marriage was legally approved in 2010, and same-gender adoption in 2016. Noteworthily, the data used in this study was collected before the final approval of the same-gender adoption law.

The Present Study

Based on the aforementioned findings, the purpose of this study was to empirically assess if the level of support/rejection of same-gender marriage and same-gender parenting is associated with attitudes toward gay men and lesbians and with beliefs about the etiology of homosexuality, as part of a general belief system conceptually defined as Sexual Prejudice (Herek, 2009). Specifically, we hypothesize that the impact of gender, religious beliefs, and political leaning on the support for same-gender marriage and parenting is mediated by etiological beliefs and attitudes toward gay men and lesbians. Further, we hypothesize that etiological beliefs may serve to justify sexual prejudice and, thus, be associated with attitudes toward gay men and lesbians, and support for same-gender marriage and same-gender parenting.

Method

Participants

The sample consisted of 704 Portuguese individuals who participated in an online survey about university students’ attitudes toward same-gender marriage and same-gender parenting in Europe. The participants were all self-identified heterosexuals (24% men and 76% women), aged between 18 and 30 years (M = 22; SD = 3). Participants were university students, with the vast majority currently enrolled in an undergraduate degree (86%), 10% in a master degree, and 4% in other postgraduate degrees. Numbers of years of study ranged from 13 to 25 (M = 15, SD = 2). Close to one third of the participants were studying social and human sciences, 18% were studying natural sciences and engineering, 14% were studying medical and health sciences, and the remainder were studying other fields. Geographically, all 308 Portuguese councils were represented in this sample, although most participants were from larger populated districts, and 93% of participants reported having a Portuguese nationality. Regarding religious beliefs, 51% of the participants identified as Catholics, 9% as agnostic, 33% as atheists, and the remainder with other religious beliefs. Complete sociodemographic data are presented in Table 1.

Table 1 Sociodemographic characteristics
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An initial sample of 1275 participants was collected. From these, 220 were excluded from the study for not being enrolled in a university degree; 164 for self-identifying as other than heterosexual; 9 for not reporting their gender, sexual orientation, or age; and 178 for not completing the same-gender marriage and same-gender parenting questionnaires. Final sample was 704.

Measures

Participants were asked to complete a sociodemographic questionnaire developed for this study, a series of questions about their support for same-gender marriage and same-gender parenting, a scale measuring negative attitudes toward gay men and lesbians, and a scale measuring etiological beliefs of homosexuality.

Sociodemographic and Attitudinal Variables

Among the sociodemographic and attitudinal variables, age, gender, relationship status, having children, years of study, religiosity, importance of religion, and political leaning were assessed and included in the analyses. Age and years of study were measured as continuous variables. Being in a relationship and having children were collapsed and dummy coded to create single dichotomous variables: 0 (single) and 1 (committed), and 0 (no children) and 1 (children). Gender was represented as 0 (women) and 1 (men). Religiosity (“How frequently do you attend religious services?”) was measured on a 6-point Likert scale (from 0—never to 5—at least once a week), and importance of religion (“How important is your religion to you?”) was measured on 5-point Likert scale (from 1—not at all important to 5—extremely important). Political leaning was measured on a 5-point Likert scale (from 1—extreme left-wing to 5—extreme right-wing).

Support for Same-Gender Marriage

The support for same-gender marriage was measured using the Katuzny and Green Same-Sex Marriage Questionnaire (SSM; D’Amore et al., 2017). Participants were asked (1) “How supportive were you when you first heard about same-gender marriage”; (2) “How supportive are you now of same-gender parented families?”; and (3) How supportive are you of international recognition of same-gender marriages across countries? all measured on a 6-point Likert scale (from 1—extremely not supportive to 6—extremely supportive). Participants were further asked where they first heard about same-gender marriage (measured as 1—in a political speech or in the media, 2—through a friend, 3—through a colleague or acquaintance, 4—through a family member, 5—through other means).

Support for Same-Gender Parenting

The support for same-gender parenting was measured using the D’Amore and Green Same-Sex Parenting Questionnaire (SSP; D’Amore et al., 2017). Participants were asked (1) “How supportive were you when you first heard about same-gender families”; (2) “How supportive are you now of same-gender marriage?” measured on a 6-point Likert scale (from 1—extremely not supportive to 6—extremely supportive). Participants were further asked where they first heard about same-gender marriage (measured as 1—in a political speech or in the media, 2—through a friend, 3—through a colleague or acquaintance, 4—through a family member, 5—through other means). To assess the support for different paths to parenthood available to gay men and lesbians, participants were asked about their support for (1) adoption by single lesbians; (2) adoption by single gay men; (3) adoption by lesbian couples; (4) adoption by gay couples; (5) donor insemination; (6) in vitro fertilization; and (7) surrogacy (all measured as 0—not supportive or 1—supportive).

Attitudes Toward Gay Men and Lesbians

Attitude toward gay men and lesbians was measured using the Attitudes Toward Lesbians and Gay Men (ATLG) scale (Herek, 1998). For this study, the 5-item version was used with two subscales; one for men (ATG; e.g., “Sex between two men is just plain wrong”) and one for women (ATL; e.g., “Sex between two women is just simply wrong”), measured on a 5-point Likert scale (from 1—strongly disagree to 5—strongly agree). Cronbach’s alpha for this study was high for both scales (α ATG = .812; α ATL = .812), and the correlation between the two subscales was very high (r = .936, p < .001).

Etiological Beliefs of Homosexuality

Etiological beliefs of homosexuality were measured using a brief scale measuring beliefs about the developmental origins and perceived controllability of homosexuality (Costa et al., 2014). This scale consists of six items measuring the most common beliefs about what makes a person gay/lesbian. All items were measured on a 5-point Likert scale (from 1—strongly disagree to 5—strongly agree). Internal reliability, inter-item correlations, and correlations with attitudes toward gay and lesbian rights and attitudes toward gay and lesbian parenting have provided evidence of concurrent and convergent validities (Costa et al., 2014). Cronbach’s alpha for this study was high (α = 0.717).

Procedures

Participants were recruited online through contacts with Portuguese universities. An email with a general description of the study, a link to the online survey, and inclusion criteria for the study were sent to universities, along with a request for distribution through their students’ emailing lists. Inclusion criteria were that participants were at least 18 years and currently enrolled in university. The online questionnaire was hosted on SurveyMonkey, and the data was collected between 2012 and 2014.

On the first page of the questionnaire, participants were informed about how to complete the questionnaire, how to withdraw from the study, and that participation was voluntary and anonymous. No compensation was offered to participants. Before moving on to the questionnaire, participants were asked for their consent to participate. The same procedures were implemented in the seven participant European countries—Belgium, France, Greece, Italy, Poland, Portugal, and Spain. All procedures were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Data Analysis

The data were analyzed using the Predictive Analysis Software (PASW) Statistics version 21 and the Analysis of Moment Structures (AMOS) version 21. PASW was used to conduct descriptive statistics; to assess differences across groups on levels of support for same-gender marriage and parenting, attitudes toward gay men and lesbians, and etiological beliefs; and to investigate the correlations among sociodemographic variables, levels of support for same-gender marriage and parenting, attitudes toward gay men and lesbians, and etiological beliefs. AMOS was used to develop the path analysis model.

The path analysis model was estimated using the robust maximum likelihood estimator. The significance of direct, indirect, and total effects was evaluated with χ 2, and an alpha level of 0.05 was used to determine statistical significance. The magnitude and significance of the mediated and direct effects were estimated using bootstrap procedure, generated from 1000 samples, as recommended for mediation analysis (Hayes, 2009). This procedure is considered more appropriate than traditional mediation analyses by not requiring that predictor variables are normally distributed (Hayes, 2009). All variables were introduced as observed variables. Model fit was assessed using the chi-square test, the comparative fit index (CFI), the Tucker-Lewis Index (TLI), and the root mean square error of approximation (RMSEA). Values above 0.90 on the CFI and on the TLI and below 0.10 on the RMSEA are indicators of an acceptable model fit. Values above 0.95 on the CFI and on the TLI and below 0.05 on the RMSEA are indicators of good model fit (Hair, Black, Babin, Anderson, & Tatham, 2006).

Results

The majority of the participants first heard about same-gender marriage (59%) and same-gender parenting (64%) through political speeches and/or in the media (Table 2). The vast majority of participants were favorable to all the different paths to parenthood available to gay men and lesbians, although they tended to be more supportive of adoption by same-gender couples than by single gay men and lesbians. Noteworthy, surrogacy seemed to be more contentious, as just slightly over half of the sample was favorable to this path to parenthood (Fig. 1).

Table 2 Sources of information about same-gender marriage (SGM) and same-gender parenting (SGP)
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Fig. 1
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Percentages of support for different same-gender pathways to parenthood for the total sample, and separately for men and women

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To assess whether participants reported any self-report change in their attitudes toward same-gender marriage and same-gender parenting from the first time they heard about it and the present time, paired samples t tests were conducted. Results showed that participants’ acceptance of same-gender marriage, t(703) = −13.93, p < .001, d = .32, and same-gender parenting, t(703) = −13.66, p < .001, d = .30, has significantly improved (Table 3).

Table 3 Degree of support for same-gender marriage (SGM) and same-gender parenting (SGP) among the total sample, and separately for men and women
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To examine whether there were differences between the degree of support for same-gender marriage and same-gender parenting at the present time, a one-sample t test was conducted. Results showed that participants were significantly more likely to support same-gender marriage than same-gender parenting, t(703) = 82.74, p < .001, d = .32. Similar results were found for both men, t(167) = 30.91, p < .001, d = .29, and women, t(535) = 81.93, p < .001, d = .36, separately (Table 3). Noteworthily, men were mostly against same-gender marriage and same-gender parenting when they first heard about it, but about half of them were still not supportive of both marriage and parenting at present time.

To assess whether there were differences between men and women on attitudes toward gay men and lesbians and on etiological beliefs about homosexuality, a one-way ANOVA was conducted. Results showed that men held significantly higher levels of negative attitudes toward gay men, F(1, 704) = 46.65, p < .001, ƞ 2 p = 0.062, toward lesbians, F(1, 704) = 22.20, p < .001, ƞ 2 p = 0.031, and stronger beliefs of a controllability of homosexuality, F(1, 704) = 46.74, p < .001, ƞ 2 p = 0.062, than women (Table 4).

Table 4 Etiological beliefs, attitudes toward gay men and lesbians among the total sample, and separately for men and women
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Predicting Support for Same-Gender Marriage and Same-Gender Parenting

Prior to testing the path analysis model of support for same-gender marriage and same-gender parenting, the associations among the variables were assessed through bivariate correlations. Among the sociodemographic variables, age, being in a relationship, having children, and years of study were not significantly associated with etiological beliefs, attitudes toward gay men and lesbians, or with support for same-gender marriage and parenting. Only gender, political leaning, religiosity, and importance of religion were significantly associated with etiological beliefs, attitudes toward gay men and lesbians, and support for same-gender marriage and parenting, and were thus included in the mediation analysis (Table 5).

Table 5 Correlations among sociodemographic variables, etiological beliefs, attitudes toward gay men and lesbians (ATLG), support for same-gender marriage (SGM) and same-gender parenting (SGP)
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To examine the effects of gender, political leaning, religiosity, and importance of religion on support for same-gender marriage and same-gender parenting, and to test the hypothesized mediation of etiological beliefs and attitudes toward gay men and lesbians, a path analysis model was developed. The initial model included both direct and direct effects, and showed satisfactory fit, χ 2(6) = 176.99, p < .001, CFI = 0.928, TLI = 0.666, RMSEA = 0.201 90% CI [0.176, 0.227]. No evidence of violations to the normal distribution was found (Kline, 2010). Religiosity did not have direct effects on support for same-gender marriage or parenting, or on etiological beliefs. Importance of religion did not have a direct effect on support for same-gender parenting or sexual prejudice; thus, these trajectories were constrained to zero. After these changes, model fit improved, χ 2(10) = 49.693, p < .001, CFI = 0.983, TLI = 0.953, RMSEA = 0.075 90% CI [0.055, 0.097]. Figure 2a depicts only significant direct effects, and Fig. 2b depicts only significant mediated effects.

Fig. 2
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a Direct effects on support for same-gender marriage (SGM) and support for same-gender parenting (SGP). b Mediated effects on support for same-gender marriage (SGM) and support for same-gender parenting (SGP)

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As expected, gender was significantly associated with etiological beliefs, attitudes toward gay men and lesbians, support for same-gender marriage, and support for same-gender parenting. As such, the effects of gender were direct to the support for same-gender marriage and parenting, but also partially mediated by both etiological beliefs and attitudes toward gay men and lesbians. Similarly, political leaning also had significant direct effects on the support for same-gender marriage and parenting, and mediated effects via etiological beliefs and attitudes toward gay men and lesbians. The effects of religiosity on the support for same-gender marriage and parenting were fully mediated by attitudes toward gay men and lesbians. The importance of religion had a significant direct effect on the support for same-gender marriage, but its effects on the support for same-gender parenting were partially mediated by etiological beliefs. Lastly, the effects of etiological beliefs on both the support for same-gender marriage and the support for same-gender parenting were partially mediated by attitudes toward gay men and lesbians. Significant effects are shown in Table 6.

Table 6 Direct and mediated effects on support for same-gender marriage (SGM) and same-gender parenting (SGP)
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Discussion

This study sought to assess sexual prejudice, specifically attitudes toward gay men and lesbians, same-gender marriage, and same-gender parenting in a large sample of Portuguese young adults. The majority of participants were supportive of same-gender marriage and same-gender parenting, although they were significantly more supportive of same-gender marriage than of same-gender parenting. This finding corroborates previous studies conducted in Portugal (Costa et al., 2014) and across Europe (Commissioner for Human Rights, 2011), but are in contrast with finding from the USA, which had shown that attitudes toward same-gender marriage were more negative than attitudes toward same-gender parenting (Gallup Organization, 2013; Schwartz, 2010).

In Europe, the recognition of parenting rights of same-gender couples has received stronger opposition and is taking longer to achieve than civil partnerships or marriage. Both young men and women in this sample were significantly more supportive of same-gender marriage than of same-gender parenting. Moreover, their initial level of support was low, with under a third of heterosexual young men being supportive of same-gender parenting, just slightly more than the 20% of support from the general population (Commissioner for Human Rights, 2011). There are two possible explanations for this finding. On the one hand, a significant number of arguments against same-gender parenting focuses on the “child’s best interest.” This common expression in Portugal has been used to condemn gay and lesbian parents as being unable to provide a loving and stable family to a child, to provide them with the necessary masculine/feminine figures, and to provide them with heterosexual role models. A further argument has been that children will likely be victimized in school because society is not ready to accept these families (Costa et al., 2013). These arguments are also in line with those identified by Clarke (2001) in the UK, while the legalization of same-gender parenting was being disputed. On the other hand, the legalization of same-gender marriage in Portugal in 2010 was achieved with a provision specifically prohibiting same-gender couples from adopting or from using assisted reproduction. As such, even political discourses that were supportive of same-gender marriage further reinforced sexual stigma regarding same-gender parenting.

However, support for same-gender marriage and parenting has been growing in the last few years, particularly among youth. This trend has been documented in the USA (Baunach, 2012), although in Europe little is known about the evolution of these attitudes. Furthermore, there is a large heterogeneity across European countries regarding attitudes toward same-gender marriage and parenting on the one hand, and regarding the legal recognition of these families on the other hand (Commissioner for Human Rights, 2011). Specific to Portugal, the recognition of same-gender relationships and families has been thoroughly debated for the last decade, which might help explain some contradictory findings. Costa et al. (2014) reported a high prevalence of sexual prejudice regarding same-gender parenting in a sample of university students, although other studies conducted by the same team found that despite the existence of these negative beliefs, the majority of heterosexual participants were supportive of same-gender parenting (Costa et al., 2013, 2015).

Media may play an important role in shaping individuals’ perspectives of sexual minorities (Levina, Waldo, & Fitzgerald, 2000; Lee & Hicks, 2011). The majority of participants in this study were first told about same-gender marriage and parenting through political speeches and/or in the media, and the majority eventually developed acceptant attitudes. In fact, in the last 6 years, there have been several media pieces portraying same-gender parented families as well as affirmative political campaigns supporting the legalization of adoption and assisted reproduction for same-gender couples. Adoption has been the most discussed pathway to parenthood, which helps to explain why this was the most supported pathway to parenthood in this study. This finding offers further support for the role of positive and affirmative portrayals and of political institutions in confronting structural stigma.

As expected, women were more supportive of same-gender marriage and same-gender parenting then men, and the evolution of these attitudes was also more positive among young women than among young men. Moreover, women were less prejudiced toward gay men and toward lesbians, and held weaker beliefs of a social etiology of homosexuality. All of these findings are in line with previous studies (Costa et al., 2014, 2015; Frías-Navarro, Barrientos-Delgado, Badenes-Ribera, Monterde-i-Bort, & Cárdenas-Castro, 2013). Also, in line with previous studies are the findings related to the effect of religious beliefs and political affiliation in the support for same-gender marriage and same-gender parenting (see, for example, Whitley, 2008; Whitley & Lee, 2000).

Etiological beliefs of homosexuality and attitudes toward gay men and lesbians partially mediated the effects of gender, political leaning, importance of religion, and religiosity. A growing number of studies have investigated the value of beliefs on a controllability of homosexuality to the development and maintenance of sexual prejudice (Hans et al., 2012; Sheldon et al., 2007). However, only a handful of studies have explored the value of these beliefs in predicting attitudes toward same-gender marriage and same-gender parenting, and to our knowledge no study has explored the interactions between them in explaining attitudes toward same-gender marriage and same-gender parenting (Frías-Navarro et al., 2013, 2015; Rye & Meaney, 2010).

We found in this study that perceiving homosexuality as socially influenced was significantly associated with stronger sexual prejudice. The associations between etiological beliefs and attitudes toward gay men and lesbians and between attitudes toward gay men and lesbians and support for same-gender marriage and same-gender parenting were very strong (SE >0.50). As such, there is further evidence that social/environmental beliefs about the etiology of homosexuality are strong predictors of negative attitudes toward gay men and lesbians, which negatively impact the support for same-gender relationships and families. Heterosexual men, who are highly religious and politically conservative, are also more likely to endorse social/environmental beliefs about gay men and lesbians, which partially explain their rejection of same-gender marriage and parenting. This finding helps to cast light on the dynamics of institutional prejudice. It is suggested that religious teachings oppose same-gender relationships based on the assumption that same-gender behavior is controllable, thus gay men and lesbians are accountable for their (“deviant”) sexual preferences, and are morally reprehensible for their attractions and behaviors.

In another instance of institutional prejudice, the effects of political leaning were also mediated by etiology beliefs and attitudes toward gay men and lesbians, although these associations were weaker than those found for religious beliefs. Considering that the dynamics of sexual prejudice seem to be to a certain extent rooted in the belief that homosexuality is controllable, the perceived responsibility over same-gender preferences justifies an opposition to the recognition of same-gender relationships that exists in the form of individual stigma, which are reinforced by religious and political institutions. These dynamics are more likely to remain undisputed among men, older and less educated people (Baiocco, Nardelli, Pezzuti, & Lingiardi, 2013; Grapes, 2006; Hollekim et al., 2012; Kirby & Michaelson, 2008), who should be targeted in interventions and policies to reduce sexual prejudice.

Limitations

There have been some limitations to this study that must be acknowledged. The first limitation regards the data collection procedures. Online survey approaches enable researchers to collect large datasets, but it also presents some weaknesses, namely, a self-selection bias. It may have been the case that participants with more accepting attitudes were more likely to take part in the present study. A further limitation was the larger proportion of women in the sample, who were shown to be less prejudiced than men, and because of that may have skewed the results in the direction of more favorable attitudes toward gay men and lesbians, same-gender marriage, and same-gender parenting. Another limitation was the data collection with an educated and fairly young sample. These sample characteristics may have inflated or attenuated some of the relations between variables. To the extent that results from this study could be generalized to the Portuguese population cannot be determined.

Regarding the measures used in this study, there have also been some limitations that are important to be acknowledged. The evolution of acceptance of same-gender marriage and parenting as measured in this sample has relied on participants’ retrospective, and thus subjective perceptions. We have not measured the amount of time between the first time participants heard about same-gender marriage and parenting and the present time. We suspect that given their young age, the amount time may not have been long. Furthermore, the sources of information about same-gender marriage and same-gender parenting political—speeches and media—had been measured with only one question. Perhaps separating these two sources would have provided more specific information, and shown some differences between them. We argue, however, that political speeches are mostly seen via the media; thus, separating these two sources may have proven difficult. Lastly, although we have used sophisticated multivariate methods to assess sexual prejudice, this study was cross-sectional, and thus causality cannot be ascertain.

Conclusions

This study extended previous knowledge about the attitudes and the support for same-gender relationships and families. While there is abundant research about individual differences on levels of sexual prejudice toward gay men and lesbians, the study of sexual prejudice toward gay and lesbian relationships and families is still beginning, particularly about the dynamics of prejudice. It was shown that attitudes toward same-gender marriage and parenting in Portugal have improved, and the majority of young adults are supportive of the recognition and legalization of these families. It was also suggested that the media may have played an important role in improving these attitudes, as the overwhelming majority of participants first heard about same-gender marriage and parenting in the media and/or through political discourses. Noteworthily, same-gender marriage and parenting had been thoroughly debated in Portugal for the last decade, starting from the legalization of same-gender marriage in 2010, until the legalization of adoption by same-gender couples in 2016. Within this time-frame, there had been several positive mainstream media portrayals about the difficulties and struggles of unrecognized family relationships, as well as empowering messages about the resilience and well-being of both parents and children in these families. Institutional correction of discrimination against same-gender relationship is therefore suggested to have practical implications in combating sexual prejudice.

Considering the growing number and increasing visibility of gay and lesbian families throughout Europe, societal scrutiny may pose additional stress and threats to family well-being. Furthermore, sexual prejudice is detrimental to the well-being of same-gender couples and gay- and lesbian-led families, and may lead to social isolation, felt stigma, discrimination, and victimization of both parents and children in different social contexts. Uncovering the roots and dynamics of sexual prejudice is thus pivotal to combat its effects and to prevent the victimization of same-gender parented families.