Related to this, mononormativity presumes that pair bonds should be between two individuals only, marginalizing (a) people with partner number sexualities beyond one, as with those in multiple relationships, as well as (b) those who are single or not interested in being in relationships with other people, as with people who are Aromantic, single-by-choice, focused on sexual-erotic contacts only and more. Mononormativity and heteronormativity both reflect a sexual normativity, that people should be and/or should want to be sexual with someone else, marginalizing Asexual people. These normativities have meant that most human biobehavioral research on partnered sexuality/relationality has focused on biologically reductionist topics, for example, which hormones account for pair bonds or will promote monogamy over “promiscuity.” Biological expansiveness/emergence offers a different approach. In SCT, people can be understood to not be sexual and/or to not have desire to be sexual with others (van Anders, 2015), or to only be connected with others in erotic but not nurturant ways, all of which accords with many lived experiences. Or, for example, the S/P Theory starts with hormones but provides a rich model for approaching pair bonds (see Figure 3) TABLES AND FIGURESView larger image > in this page > in popup window| Thumbnail view> Download Powerpoint slide (.ppt) The downloadable content is an alternative presentation to the accessible web content and may not conform to WCAG 2.1 AA.Figure 3. Models of Pair Bonds by Partner Number Outside of Biologism, Binaries, and MononormativitiesNote. J and K are each in a “two-point pair bond” (i.e., one pair bond each that is with each other). L and N are in “embedded two-point pair bonds” with M, P, or Q (i.e., one pair bond each with a partner who has a pair bond with them and another/others). M is in a “multipoint pair bond” with L and N (i.e., M has multiple pair bonds who are each in a pair bond only with M). P and Q are in “embedded multipoint pair bonds” (i.e., they have multiple pair bonds, some of whom also have multiple pair bonds). Arrows represent the direction of the bond (in this case, all partners are pair bonded with each other; in other cases, someone might be pair bonded with a partner who is not pair bonded with them). These different forms of pair bonds may have implications for hormones specifically or biobehavioral research in general, as well as other psychological, relational, behavioural, and sociocultural aspects. Adapted from “The Steroid/Peptide Theory of Social Bonds: Integrating testosterone and peptide responses for classifying social behavioral contexts,” by S. M. van Anders, K. L. Goldey, and P. X. Kuo, 2011, Psychoneuroendocrinology, 36(9), pp. 1265–1275 (https://doi.org/10.1016/j.psyneuen.2011.06.001). Copyright 2011 by Elsevier. Adapted with permission. See the online article for the color version of this figure.Figure 3. Models of Pair Bonds by Partner Number Outside of Biologism, Binaries, and MononormativitiesNote. J and K are each in a “two-point pair bond” (i.e., one pair bond each that is with each other). L and N are in “embedded two-point pair bonds” with M, P, or Q (i.e., one pair bond each with a partner who has a pair bond with them and another/others). M is in a “multipoint pair bond” with L and N (i.e., M has multiple pair bonds who are each in a pair bond only with M). P and Q are in “embedded multipoint pair bonds” (i.e., they have multiple pair bonds, some of whom also have multiple pair bonds). Arrows represent the direction of the bond (in this case, all partners are pair bonded with each other; in other cases, someone might be pair bonded with a partner who is not pair bonded with them). These different forms of pair bonds may have implications for hormones specifically or biobehavioral research in general, as well as other psychological, relational, behavioural, and sociocultural aspects. Adapted from “The Steroid/Peptide Theory of Social Bonds: Integrating testosterone and peptide responses for classifying social behavioral contexts,” by S. M. van Anders, K. L. Goldey, and P. X. Kuo, 2011, Psychoneuroendocrinology, 36(9), pp. 1265–1275 (https://doi.org/10.1016/j.psyneuen.2011.06.001). Copyright 2011 by Elsevier. Adapted with permission. See the online article for the color version of this figure. that includes but goes well beyond “two-point” pair bonds to reflect the empirical reality of partner number sexual and relational diversity, for example, pair bonds that are “embedded two-point,” “multipoint,” and “embedded multipoint” as well as two-point (van Anders et al., 2011). Biobehavioral models can thus provide ways to think expansively about sexual and relational diversity, in ways that avoid marginalizing those on the sexual margins and instead recognizing that people with diverse partner number sexualities exist, and flourish.

Biologisms are problematic in and of themselves as described above but also because of their ties to other kinds of regressive ideologies including sexism, cisnormativity, heteronormativity, and mononormativity. Biobehavioral research beyond biologisms helps to address and attend to these. For example, biological contextualism can help provide scientific approaches beyond sexism, a usually biologically essentialist ideology that fits all people into men/boys or women/girls and marginalizes women/girls. Biological contextualism makes clear how seemingly innate differences can actually reflect varied social processes. Assumptions about female biology can make this point: there are higher rates of knee injuries among women/girls playing sports than among men/boys that are typically presumed to reflect innate “female biology.” But biological contextualism highlights how these injuries can actually reflect the physical embodiment of gender inequities in access to activity, open spaces, and sport itself (i.e., that these impact knee, bone, and muscle development)—and thus relate to key questions of gender in a biobehavioral research question (why do men/boys experience fewer of these knee injuries during sport than girls/women?; Parsons et al., 2021).

Moreover, because of gender norms, behaviours may be so common that they no longer even trigger hormonal responses due to acclimatization, physiological “tolerance” or habituation, or desensitization. For example, some evidence suggests that sexual thoughts are more likely to increase testosterone in women, and nurturance to decrease it in men (Goldey & van Anders, 2011, 2012), and this may reflect the very different kinds of socialization toward sexual thoughts (natural for men! dirty for women!) and stimuli (highly prevalent images of sexualized women). As such, engaging in the “same” behaviors can impact testosterone in differential ways given how gendered contexts can change the meaning or actions of the behaviors. Gender can thus have biomaterial impacts, modulating testosterone in acute, state-like ways. Whether we have high or low testosterone might at least partially depend, not just on our genetics but what we, as gendered beings, do.

Biomaterial, biological/evolved, and bodily/physical characterize aspects5Footnote 5 Aspects of sex can also be understood as enactments of sex as per Mol (2002): Enactments are specific definitions of phenomena that focus on ontology, phenomenology, and/or function, and they can be competing or even incommensurate. When aspects of sex are defined for the purpose of understanding or conceptualization, they are enactments. But, when they are defined for the purpose of measurement, they are operationalizations. Both enactments and operationalizations are used when there is no singular, objective definition of a phenomenon, but only definitions-in-context, e.g., for the purposes of usage. See also (Latham, 2017) for a compelling account of this.hide footnote of sex, which are critical to the definition: sex is multiple and multifaceted, describing plural phenomena that can be variably configured as many have shown and argued (e.g., Fausto-Sterling, 2020; Latham, 2017). This also contributes to a definition of sex that is empirical, accurate, and just. For example, that sex is plural and multifaceted is illustrated by the vast array of and variety in aspects people have used and continue to use to define sex in science, policy, and everyday usage over time, place, and discipline (Currah, 2022; Fausto-Sterling, 2020; Jordan-Young, 2010; Latham, 2017; van Anders, 2015; van Anders et al., 2017). As a nonexhaustive list, definitions of sex have included/do include: genitals (size, form, and/or function), internal sex (e.g., uteri; gamete function or size6Footnote 6 Larger gamete size was used to define femaleness in birds and mammals before genotyping. Yet female birds and male mammals are largely heterogametic and share other features, like earlier death (Xirocostas et al., 2020).hide footnote), hormones (e.g., levels, responses, action), neural regions, gametes (size, function), skull size, secondary sex characteristics (e.g., facial hair, fat deposition, breast development), ability to conceive or inseminate, gestation ability or history, chromosomes (e.g., XX or XY, SRY genes, WW/WZ), and many more. Beyond these, definitions of sex have also included—however counterintuitively—social behaviours (e.g., a real/natural woman is a good mother; boys are naturally rough-and-tumble), expression (e.g., girls inherently are drawn to frilly things, boys naturally do not like pink), gender/sex sexuality (e.g., men are naturally highly sexed/attracted to women), and intersecting axes of oppression (e.g., majoritarian culture positioned white women as a different sex from unfree Black women and still differentially sexes women by race/ethnicity; Bailey, 2016; Fausto-Sterling, 2020; Jordan-Young, 2010; Snorton, 2017). Indeed, sex has been and still is racialized and derived from colonial and settler colonial taxonomies in ways that situate normative sex within whiteness, classism, and European hierarchy (for example, characterizing femaleness as weaker/less strong than maleness, despite the reality that racialized and/or low-income women have done and often do heavy strength-based labor, sometimes to the exclusion of men, and frequently not by choice; Lugones, 2007; Markowitz, 2001; Stein, 2015; Stepan, 1986, 1998).

Biological/evolved is a prevalent definitional feature of sex and refers to living processes/materials that arise endogenously as an outcome of evolved processes. For example, biological/evolved aspects of sex can include the development and activation of mammary glands in response to pubertal, adult, pregnancy-related, and lactation-related stimuli, which can produce milk to help infants survive. Biomaterial is a critical and underappreciated definitional feature of sex, referring to living processes/materials that have been introduced or result from exogenous impacts. For example, biomaterial aspects of sex can include voice changes resulting from exogenous hormone use. Finally, bodily/physical is also a critical and underappreciated definitional feature of sex that actually reflects common usage; it refers to phenomena tied to bodies and/or physicalities, including material objects, substances, and practices that shape and/or modify bodies. For example, chest binding is bodily/physical in that it involves shaping chests, and it also can be bodily/physical or biomaterial in the sense that it can modify chest tissue. Similarly, packing or tucking can be bodily/physical: they both involve physical and bodily aspects, and modify people’s bodily sex as they and/or others understand them. Defining sex as biological/evolved, biomaterial, and bodily/physical is key to understanding what sex is in ways that are empirical, accurate, and just. And while not everyone or every aspect of sex requires all three, or requires them to be differentiated, they are useful as potentially separable constructs. For example, biological/evolved makes space for definitions of sex that rely on evolved features, that are innate or genetic (e.g., XX, XY, XXY, XO, XYY, etc., chromosomal configurations), whereas biomaterial makes space for those that are biological but not evolved, innate, or genetic, but still widely understood to reflect and be meaningful for or to sex (e.g., breasts that have grown in response to use of hormones). These points are clarified by understanding where sex is located.

My own interdisciplinary position and social location informs this article and the ideas within it, as all of ours do for all of our work, whether we recognize this or not, as scholars have compellingly shown and argued (e.g., Haraway, 1988). My academic homes include psychology, neuroscience, feminist/gender/women’s studies, and feminist/queer science studies, and my work is adjacent to and/or informed by disciplines that include sociology, philosophy, anthropology, cultural studies, health, and more. My Ph.D. was in behavioral neuroscience (called biological and cognitive psychology at that institution at that time). My dissertation research was rooted specifically in behavioral neuroendocrinology, and I was one of a group who began articulating a field of social neuroendocrinology (van Anders & Watson, 2006). But my academic engagements and communities went well beyond, to sex research, intersex studies, feminist psychology, queer studies, trans studies, and more. I thus “grew up” at the interconnections of many disciplines, including those that critiqued each other or had “across-the-aisle” epistemologies, and made my home(s) in that fraught space, working to construct innovative models of and theories for biobehavioral research informed by and meaningful for gender/sex/ual diversity. This process was also informed by aspects of my own social location, which include several interstitial existences/experiences/identities, the most relevant of which for this article might be queer by orientation, queer-ish by identity, and status of being a woman partnered with one man. My gender/sex/ual location and academic location have provided a gender/sex/ual lived experience and an academic expertise that made possible my research program on social neuroendocrinology, gender/sex and sexual diversity, sexuality, and feminist/queer science. This all has provided me with a range of experiences and expertise that has made for a strong and critical foundation for articulating a more empirical, accurate, and just foundation for biobehavioral research and gender/sex/ual diversity in this article.

Biologism and the sex–gender binary create other issues for biobehavioral research, because they are arguably caught up with other regressive, harmful, and antiempirical ideologies like cisnormativity, heteronormativity, sexual normativity, and mononormativity.3Footnote 3 Each of these refers to beliefs, attitudes, structures, and assumptions that privilege the majority case and erase, marginalize, or other those minoritized on the relevant axis: cisnormativity majoritizes cisgender existences, heteronormativity majoritizes heterosexual ones, sexual normativity majoritizes those who have sexual attractions to and/or interests in being sexual with others, and mononormativity majoritizes those who want to be/are in sexual/romantic relationships with only one other person (Carrigan et al., 2014; Emens, 2004; Serano, 2007).hide footnote For example, discussions of sex are often used to buttress cisnormativity, as if sex assigned at birth was a coherent and universal phenomenon canalizing a singular lifelong gender trajectory. This marginalizes many, including those who are transgender, intersex, Two-Spirit/Multi-Spirit, and/or nonbinary, as well as many other gender/sex minorities.4Footnote 4 I use “minorities” and “minoritized” to refer to minoritized and marginalized positions in power hierarchies, and “majorities” and “majoritized” to refer to privileged and overempowered positions in power hierarchies, and neither to reference statistical infrequency (van Anders, 2015). Like all terms, these are imperfect; I use them despite their harms when I mean not only to reference identities but also experiences and existences that would otherwise be excluded from an identity term.hide footnote Deployments of sex also buttress heteronormativity, by positioning female and male sex as prescriptively complementary to each other. This also marginalizes many, including those who are lesbian, gay, queer, bisexual, pansexual, and many other sexual minorities. The assumption that sexuality is “natural” as well as an inherent, universal aspect of humanity upholds sexual normativities. These marginalize those who are Asexual or Demisexual, and makes those experiencing low sexual desire for other experiential reasons question their health and wellbeing. And, the assumption that monogamy is natural, “hard-wired,” and desirable supports mononormativities. These marginalize those who are polyamorous, in open relationships, or who have multisexual existences, orientations, statuses, and/or identities. All of these ideologies also harm majorities by policing all of us, assuming our gender/sex/ualities are static and unchanging, and mandating our existences along normative, majoritarian gender/sex/uality lines. And they do so in close partnership with other regressive ideologies, like colonialism and settler colonialism, racism, sexism, and more, because they make hierarchies of sexed peoples and the nations they are connected to by how close they are to white supremacist and Eurocentric ideals (Lugones, 2007; Markowitz, 2001). How gender/sex/uality is constructed viz-a-viz sex–gender binaries and their concomitant biologisms matters for psychology, including for the methods of our research, the questions we ask, who is included in our research, and what kinds of harms and benefits our research process and products carry, and to whom.

One reason why transcending sex–gender and nature-nurture/culture binaries is so important is because these binaries are rooted in “biologism,” the belief that biology is the best and/or only way to provide meaningful knowledge about life. Biologism is a particular form of “scientism,” which is the widespread belief that science is the only/best way to know about the world. Biobehavioral research—whether in psychology, biology, or another discipline—is often biologistic but does not have to be. In other words, biobehavioral research is biological but not inherently biologistic. However, that biobehavioral research tends to be biologistic means that people often take the sex and nature side of binaries as evidentiary or phenomenological trump cards, ignoring or sidelining research related to gender, nurture, and culture. Biologism thus increases the stakes of the gender binary, because biologism supports the deployment of the gender binary to essentialize and then restrict gender/sex/uality as well as the rights of gender/sex/uality groups2Footnote 2 I use “gender/sex/ual” or “gender/sex/uality” when referring to a mix of gender, sex, and sexuality.hide footnote, including those that are already marginalized (e.g., Fausto-Sterling, 2020; Latham, 2017; Spade, 2006).

The sex–gender binary and nature–nurture/culture binary make a case that the world is divisible not only into two parts but two factions. This is because these binaries pit sex against gender, and nature against nurture or culture. Yet binaries are notoriously inept at describing the world, most poignantly because they exclude realities that exist beyond them (Fausto-Sterling, 2020; Waters, 2001). For example, most people would position biological parameters like hormones on the sex and nature side of these binaries. On the surface, that makes sense: hormones are biochemical substances that move through blood, are made by endocrine glands or via other material processes, bind to hormone receptors, and influence cellular function (Nelson & Kriegsfeld, 2016). They reflect physiological processes and are the result of evolutionary selective processes. And, androgens and estrogens are even often called “sex hormones.”1Footnote 1 Androgens and estrogens are categories of hormones. The most well-known androgen is testosterone and the most well-known estrogen is estradiol. However, most people say testosterone and estrogen when referring to these hormones, eliding individual hormones and hormone categories. In this article, I will use the category when I mean that, and the specific hormone otherwise. And, though they are often referred to as “sex hormones,” estrogens and androgens are involved in many non–sex-related phenomena like immunity, cardiac function, and sleep; moreover, many other hormones are relevant to sex-related processes. All this makes “sex hormones” an inaccurate moniker as well as a misleading one.hide footnote But, are hormones really always and only sex and nature? Can they reflect gender, nurture, and culture, too? In this article, I delineate how we can ask psychological and behavioral questions that include hormones specifically, and biological parameters in general, that transcend these binaries. I argue that this approach provides answers to psychological questions that include sex and nature, as well as gender, nurture, and culture, in ways that make for a transformative feminist and queer science and psychology that is more empirically accurate, rigorous, socially situated, and just.