Not quite over the rainbow: the unrelenting and insidious nature of heteronormative ideology

Heteronormative ideology refers to the belief that there are two separate and opposing genders with associated natural roles that match their assigned sex, and that heterosexuality is a given. It is pervasive and persistent, carrying negative consequences. Because it is embedded in societal institutions and propagated through socialization and other widely held ideologies, it is prevalent among both cis-hetero and LGBTQI+ individuals. In the current article, we discuss the unrelenting and insidious nature of heteronormativeideology,reviewsomeofthesocial-psychological mechanisms that contribute to its maintenance, and provide directions for future research that could inform efforts to combat it. We argue that threat reactions to non-heteronormative behavior reinforceheteronormativebeliefsandthatinterventionsareneeded to address both prejudice and its underlying mechanisms.

"Seventy percent of the people who raised me, who loved me, who I trusted, believed that homosexuality was a sin, that homosexuals were heinous, subhuman, pedophiles. 70 percent! And by the time I identified as being gay, it was too late, I was already homophobic. And you do not get to just flip a switch on that." -Hannah Gadsby, Nanette [1] The above quote by the Australian entertainer Hannah Gadsby aptly illustrates the all-encompassing power of heteronormative ideology, such that not only does it shape the way individuals view others, it can also, through internalization, shape the way individuals view themselves. Heteronormative ideology refers to the belief that there are two separate and opposing genders (women and men) with associated natural roles (masculine and feminine), which are in line with their assigned sex (female and male), and that heterosexuality is a given, rather than one of many possible sexualities [2]. Heteronormative assumptions are ubiquitous in the daily experiences of both children and adults, leading them to routinely faceand frequently reinforce-such expectations. Accordingly, heteronormativity is the lens through which the world is viewed and, importantly, through which it is evaluated and judged [3].
Heteronormativity is both descriptive and prescriptive.
People are assumed to identify with the gender that aligns with their sex and be attracted exclusively to the opposite sex because this characterizes the majority of people. Furthermore, they are often supposed to do so because it is the proper thing to do, and may otherwise face backlash (also known as transnegativity and homonegativity). Through their descriptive and prescriptive nature, heteronormative beliefs have far-reaching consequences, not only because they commonly lead to an underestimation of gender and sexual diversity and to backlash against people who deviate from these norms, such as LGBTQI+ people, 1 but also because they may serve as a straightjacket for those adhering to them. As an illustration, a straight cis-gender man who endorses the heteronormative view that children need a breadwinning father and a caring mother, for example, will likely perceive a samesex couple as lesser parents but also feel uncomfortable taking up paternity leave himself. In the current article, we discuss the unrelenting and insidious nature of heteronormative ideology, review some of the social-psychological mechanisms that contribute to its maintenance, and provide directions for future research that could provide important insight towards combating it. In doing so, we primarily focus on prescriptive heteronormativity, because its consequences are particularly harmful, including prejudice, discrimination, and even violence.

The pervasiveness and ill effects of heteronormative ideology in society
Heteronormativity not only exists in the collective minds of people but is also ingrained in the very fabric of our social, legal, economic, political, educational, and religious institutions. Its ever-present, descriptive nature is evident first-and-foremost in marriage, pregnancy, adoption, and related socio-legal practices that in most societies are beholden to different-sex couples only. Encountering heteronormative assumptions is a daily affair, with people routinely forced to pick one of two options when asked to indicate their gender or sex in systems and on forms, and with their shopping experiences generally organized along gender lines (e.g., with women's and men's clothing and girls' and boys' toy sections).
While descriptive heteronormativity entails no assumption that people who are straight and gender-conforming are morally superior, it is likely related to prescriptive heteronormativity. The literature is unclear on the exact process through which normative beliefs become moralized [4,5], but believing that the gender binary exists appears to be a necessary precondition for people to believe that it is desirable. Indeed, people have been found to anchor their perceptions of what should be on their view of what is (e.g., through processes of system justification [6]).
A far-too-common manifestation of the prescriptive nature of heteronormativity is prejudice based on sexual orientation (i.e., homonegativity or heterosexism; e.g., against bisexual, lesbian, and gay individuals) and gender identity (i.e., transnegativity; e.g., against trans women, trans men, and non-binary individuals). In other words, when heteronormative beliefs are moralized (i.e., when they are prescriptive), they can lead to the denial, denigration and stigmatization of queer and non-binary forms of behavior, identity, relationship, or community [7], which can range in form, from more blatant and explicit to more subtle and implicit [8 ,9]. These include formal restrictions on behavior that challenges heteronormativity, with laws present in at least 76 countries criminalizing consensual, adult samesex relationships, cross-dressing, cross-gender behavior, and/or even discussion of 'non-traditional sexual relations'. In extreme cases, such as in Iran, Mauritania, and parts of Somalia, such offences are punishable by the death penalty [10]. These legal restrictions are augmented by less formal forms of discrimination, with bullying of non-conforming school-age children common across the globe [10] and research suggesting that those who violate gender roles face prejudice and discrimination in social and employment situations [11][12][13][14][15] While it may be tempting to see these expressions of prejudice as an artefact of traditional societies, limited to the developing world, high levels of discrimination have also been recorded in regions seen as highly progressive, such as the European Union (EU). In fact, about half of all LGBTQI+ individuals in the EU report personal experiences with discrimination or harassment based on their non-heteronormative identities, with over 25% of them having experienced violence, and about two thirds feeling compelled to hide their identities to avoid prejudice and discrimination [16]. Even in the Netherlands, widely recognized as a pioneer in LGBTQI+ rights [17,18], 30% of LGBTQI+ individuals report experiences of discrimination and/or harassment [16], and LGBTQI+ teens face, on average, four times as much bullying as heteronormative teens [19].
There are also signs of progress. Charlesworh and Banaji [20 ], for example, showed that between 2007 and 2016, US respondents' explicit and implicit prejudice on the basis of sexual orientation showed change toward attitude neutrality. This shift corresponds to legal changes across the world, with many countries around the globe adopting stronger anti-hate crime and discrimination laws and procedures over the past decade (e.g., Albania, Cuba, Georgia, Mexico, Nepal, and South Africa), decriminalizing homosexual relations (e.g., Mozambique and Palau), and even implementing national plans of action to tackle discrimination against LGBTQI+ individuals (e.g., Brazil, France, South Africa, and Uruguay) [10]. This has led to greater visibility and acceptance, with several openly gay and openly lesbian people now serving as heads of state (of Ireland, Luxembourg, and Serbia) and same-sex marriage being legally available in 28 countries.
Despite these examples of progress, however, heteronormative ideology is pervasive and persistent. Perhaps the best illustration of this is the fact that heteronormativity is not just prevalent among those who adhere to it (i.e., sexual and gender majorities), but even among those violating heteronormative assumptions in one way or another (i.e., sexual and gender minorities). Gay men and lesbian women have been found to show weaker implicit ingroup favoritism than heterosexuals do [21,22], and to sometimes even agree with the negative opinions that society has about their group (i.e., internalized homonegativity [23,24]). Heteronormativity can also be observed in same-sex relationships, with some gay men and lesbian women either performing a feminine or masculine role (in terms of appearance and/or behavior), and dating people performing the 'opposite' role [25,26]. Interestingly, this preference for a gender-complementary partner seems particularly pronounced among those with high levels of internalized stigma when society is perceived to disapprove of homosexuality [27].
Social psychological mechanisms contributing to the maintenance of a heteronormative Status quo The pervasiveness and persistence of heteronormative ideology is not surprising when considering the social psychological mechanisms that contribute to its entrenchment and maintenance. Below, we delve into the structure and workings of heteronormativity, addressing its central role in socialization, the central role played by the gender binary in its manifestation, its overlap with other belief systems, and how the threat that non-conforming behavior and identities elicit in others facilitates the maintenance of a heteronormative status quo.
First, research has shown that descriptive and prescriptive heteronormativity are deeply ingrained in how people are socialized. Socialization in this regard refers to the identities, behavior and ideologies that parents and caretakers present to their children. More specifically, developmental research has demonstrated that children's gender attitudes are influenced by the sexual orientation of their parents and their parents' gender ideologies, and even more so by the extent to which their parents' division of labor conforms to normative gender roles [28]. Parents with more traditional gender role attitudes were also found to more frequently engage in attempts to change the gender-nonconforming behaviors of their children to fit in with societal expectations for gender [29]. Beyond the early formative years, heteronormative ideology is further bolstered by common representations in both the media and people's immediate social environment, and reinforced through the prescriptions and proscriptions in interactions with significant others and peers [30,31].
Another reason why heteronormativity is so pervasive and persistent is that it incorporates various important and central aspects of the self: one's sex characteristics, gender identity, gender expression, and sexual orientation. In addition to forming a core part of the self, these constructs are assumed to be related in systematic and meaningful ways, organized around the gender/sex binary, which refers to the belief that there are, and should be, two oppositional and complementary genders (in appearance and behavior), including sexual and romantic attraction to one another, that follow from biological sex [32 ]. The interdependence of these domains means that someone who is gender non-conforming in one domain (e.g., being a feminine-looking man) may be assumed to deviate from the gender/sex binary in other domains (e.g., be sensitive and nurturing). In other words, the gender/sex binary plays a key role within heteronormativity. Indeed, various studies indicate that the (apparent) deviation from masculine or feminine gender roles is an important aspect of negative judgements about LGBTQI+ people [8 ], and heterosexuality is a key part of gender roles, particularly for men [33].
The question remains, however, whether some aspects of heteronormativity-such as the endorsement of binary gender roles-are more central than others, and whether prescriptions and proscriptions regarding sexual orientation stem from the endorsement of binary gender roles or cause them. Some argue that heterosexuality is just one out of many aspects of gender roles [33]. In other words, because gender roles are constructed as complementary, neither women nor men are 'complete' without a relationship with the 'opposite' sex [34]. Others, however, argue that gender roles have developed in response to compulsory heterosexuality. For example, in her seminal book Gender Trouble, Butler [30] argues that gender roles developed to uphold a patriarchal system in which women's purpose is to serve as means of reproduction to men, as their mothers, and as their wives. Thus, she argues that compulsory heterosexuality came first (as a means to gain and maintain power by men), and gender norms and roles developed to maintain it.
Regardless of which aspect of heteronormativity is more central, prejudice against sexual minorities, prejudice against gender minorities, and endorsement of traditional gender roles have close connections. Accordingly, research finds that they are generally related. For example, sexual prejudice is known to be positively associated with prejudice against trans people [35], modern sexism [36], hostile sexism, and the endorsement of gender stereotypes [37]. Given how powerful and ubiquitous the gender/sex binary is, it is not surprising that heteronormativity is pervasive and hard to combat.
Heteronormativity is further supported through religious ideologies, as many religions encourage traditional gender roles and incorporate explicit heterosexism (at least with regard to sexual acts between men [38]). In line with this, religiosity is consistently related to heteronormative attitudes and beliefs such as prejudice against sexual and gender minorities [39,40], as well as benevolent sexism [41]. It is thus clear that (a) prescriptions and proscriptions regarding sexual orientation and gender roles-conforming with the gender/sex binary-are closely linked, and that (b) predictors of sexism and heterosexism are often the same (e.g., religiosity).
In a recent theoretical article, Morgenroth and Ryan [32 ] propose that disruptions to the gender/sex binary can elicit different types of threat (personal threat, groupbased and identity threat, and system threat), which in turn leads to efforts to alleviate this threat through reinforcement of the gender/sex binary. We argue that similar threat reactions contribute to the maintenance of the heteronormative belief system. For example, by challenging the one-on-one relationship between maleness and different aspects of masculinity, LGBTQI+ people can cause personal threat to men's perceived manhood, which, according to the precarious manhood literature, needs to be proven continuously and can be lost [42]. To obtain and maintain their status, men must constantly perform masculinity and avoid femininity, especially in front of other men. Being perceived as gay-or even being associated with gay men-is therefore highly threatening, and research shows that men react more negatively to gay men, particularly effeminate gay men, when their masculinity is threatened [43].
LGBTQI + individuals can also elicit group-based and identity threats such as distinctiveness threat. Members of groups (e.g., women and men) desire to see their own group as distinct and different from the outgroup [44].
LGBTQI + individuals (particularly non-binary and trans individuals) can threaten the clear distinction between "women" and "men" [45] and elicit negative reactions toward LGBTQI + individuals among women and men who are highly identified with their gender [46]. Recent research examining bisexual prejudice among lesbian women indicated that the perception that bisexual women are more sexually attracted to men than women (making them a sexual outgroup) accounts for the lesbians' negative affect toward them [47].
Lastly, LGBTQI+ individuals can elicit system threat. System justification theory [48 ] argues that individuals are motivated to defend existing systems (such as political and social structures) because they help coordinate social relationships and create a sense of shared reality, reducing feelings of uncertainty and threat. Importantly, individuals may defend such systems even if they disadvantage them, because it makes them feel better about the status quo. Indeed, LGBTQ+ individuals who minimized (versus acknowledged) the extent to which their group is the target of discrimination perceived the system as fairer and consequently reported better well-being [49 ]. Above, we have demonstrated how pervasive heteronormative beliefs are across a wide range of social systems. Not conforming to heteronormative ideals thus threaten these systems. In line with this, conservatives (who are generally high in system justification motives) strongly oppose pro-LGBTQI+ policies and practices such as gender-neutral language [50], marriage equality [51], and unisex bathrooms [52], and exhibit more sexual prejudice than liberals [53]. Conservative tendencies to uphold the status quo have furthermore been found to underlie heterosexuals' religious opposition to same-sex marriage [38] and gay men's internalized homophobia and derogation of same-sex parents' competence [54].

Conclusions and future research directions
Given that the expression of heteronormativity is pervasive, persistent and interwoven into the processes and culture of institutions, combating it is a real challenge. The social psychological mechanisms outlined above partly explain the unrelenting and insidious nature of heteronormativity and pose challenges for reducing it. These challenges are compounded by the fact that sexual orientation and gender identity prejudice is increasingly subtle [7,8 ,9,55 ]. Furthermore, the relative invisibility of sexual orientation and gender identity [56] present a unique challenge in combating heteronormativity, as LGBTQI+ individuals can to some extent avoid personal discrimination and negative reactions by staying 'closeted' [57]-a choice that has ironically been found to undermine the wellbeing of those who hide their identity [58,59], and may harm their sense of inclusion [60].
Common approaches to combating heteronormative ideology are focused on reducing sexual orientation and gender identity prejudice. A review of the literature suggests that promising interventions are those aimed at evoking empathy and perspective taking toward sexual and gender identity minorities, or at developing alliances between minority and majority members (such as Gender-Sexuality Alliances in High Schools [8 ]). However, most interventions are neither based on research nor scientifically evaluated for their effectiveness [8 ]. If we want to effectively reduce sexual orientation and gender identity prejudice, we need prejudice-reducing interventions that are robust across time and contexts and address both blatant and subtle forms of prejudice, as well as their underlying mechanisms. To this end, more research is needed on the causes of heteronormativity and on the specific relationship between heterosexism and sexism. While most theoretical perspectives view heterosexism and sexism as two sides of the same coin, no consensus has been reached on whether heterosexism is rooted in binary gender (i.e., being queer is viewed negatively because it is not in line with binary gender roles) or rather gender prejudice is rooted in sexual orientation prejudice (i.e., gender norm violations lead to backlash because they threaten heterosexuality). It is important to know the direction of their relationship in order to be able to successfully intervene. In addition, we need to not only focus on the social-psychological mechanisms contributing to the endorsement of heteronormative ideology among cis-hetero individuals but also among those making up the LGBTQI+ community themselves. A careful analysis of the social psychological processes that shape prejudicial attitudes and behaviors toward and among LGBTQI+ individuals is critical for informing theory and practice aimed at enhancing social justice, so that sexual and gender diversity cannot only be normalized but celebrated.
foregrounds binary gender/sex performance. They distinguish between character, costume, and script and argue that whenever these three dimensions are not aligned, the gender/sex binary is disrupted and gender trouble ensues.