Asexuality: Its Relationship to Sibling Sex Composition and Birth Order.

While recent research has advanced our understanding of asexuality, very little effort has been devoted to examining biomarkers and possible prenatal correlates of asexuality. In response, we recruited a large international sample (N = 1634 women and men) to explore associations between sibling composition and asexual sexual orientation (n = 366) and to replicate previously reported sibship effects in individuals with a same-sex attracted orientation (n = 276) and bisexual sexual orientation (n = 267) compared to heterosexual individuals (n = 725). Our analyses used two of the most recent statistical approaches that attempt to disentangle older sibling effects from family size effects (Ablaza et al.

Patterns of Genital and Subjective Sexual Arousal in Cisgender Asexual Men.

Human asexuality has been defined as a lack of sexual attraction to others, although its nature is not well understood. Asexual men's genital and subjective sexual arousal patterns were compared to sexual men's to better understand asexual men's sexual response patterns. Using a penile plethysmograph to measure genital arousal, 20 asexual, 27 heterosexual, and 22 gay cisgender men ( age = 28.

A short review of biological research on the development of sexual orientation.

We review research supporting biological mechanisms in the development of sexual orientation. This research includes studies on neural correlates, prenatal hormones and related physical/behavioral correlates, genetics, and the fraternal birth order effect (FBOE). These studies, taken together, have provided substantial support for biological influences underlying the development of sexual orientation, but questions remain unanswered, including how biological mechanisms may differ in contributing to men's and women's sexual orientation development.

Fraternal Birth Order, Only-Child Status, and Sibling Sex Ratio Related to Sexual Orientation in the Add Health Data: A Re-analysis and Extended Findings.

The fraternal birth order (FBO) effect related to men's sexual orientation refers to the finding that the number of older brothers that a man has increases his chance of being androphilic. The FBO effect has generally been well replicated in diverse samples; one instance of non-replication was by Francis (2008) using Waves I and III of the Add Health data. We attempted to replicate the FBO effect in the Add Health data taking into account family size and other limitations of Francis' (2008) analyses.

Male homosexuality and maternal immune responsivity to the Y-linked protein NLGN4Y.

We conducted a direct test of an immunological explanation of the finding that gay men have a greater number of older brothers than do heterosexual men. This explanation posits that some mothers develop antibodies against a Y-linked protein important in male brain development, and that this effect becomes increasingly likely with each male gestation, altering brain structures underlying sexual orientation in their later-born sons. Immune assays targeting two Y-linked proteins important in brain development-protocadherin 11 Y-linked (PCDH11Y) and neuroligin 4 Y-linked (NLGN4Y; isoforms 1 and 2)-were developed.

Personality and Sexual Orientation: Extension to Asexuality and the HEXACO Model.

Previous research has examined self-identified sexual orientation in relation to self-reports on the Big Five personality factors. Here we extend this research by including asexuality as a fourth sexual orientation and by assessing the HEXACO personality factors, using self-report data from a large anonymous online sample (N ≈ 100,000). A large overlap was observed among all sexual orientation groups on all six HEXACO dimensions, but notable group differences also emerged.

Gay Male Only-Children: Evidence for Low Birth Weight and High Maternal Miscarriage Rates.

Recent findings suggest that there may be a maternal immune response underpinning the etiology of sexual orientation of gay male only-children. This maternal immune response appears to be distinct from that which is purported to explain the classic fraternal birth order effect found in studies of male sexual orientation. We tested two predictions related to the hypothesized maternal immune response in mothers of gay male only-children: (1) elevated fetal loss among mothers who have had gay male only-children and (2) lower birth weight in gay male only-children.

Pubertal Stress and Nutrition and their Association with Sexual Orientation and Height in the Add Health Data.

A number of studies have indicated that gay men tend to be shorter, on average, than heterosexual men. Less evidence exists that lesbian women are taller, on average, than heterosexual women. The most popular explanation of the association between sexual orientation and height involves prenatal factors, such that, for example, gay men may have been exposed to lower than typical androgens during fetal development, which impacts their height and sexual orientation as adults.

Handedness, sexual orientation, and somatic markers for prenatal androgens: Are southpaws really that gay?

Background: Some evidence suggests that prenatal androgens influence both handedness and sexual orientation. This study sought to clarify how androgens, handedness, and sexual orientation are interrelated.

Methods: Data were obtained from large samples of students enrolled at universities in Malaysia and the US, including self-reported information on handedness, sexual orientation, and five somatic markers of prenatal androgen exposure (2D:4D, height, strength, muscularity, and athletic ability).

Sexual Orientation, Objective Height, and Self-Reported Height.

Studies that have used mostly self-reported height have found that androphilic men and women are shorter than gynephilic men and women, respectively. This study examined whether an objective height difference exists or whether a psychosocial account (e.g.

Asexuality: what it is and why it matters.

In this review article, human asexuality, a relatively understudied phenomenon, is discussed. Specifically, definitions and conceptualizations of asexuality (e.g.

Facial Structure Predicts Sexual Orientation in Both Men and Women.

Biological models have typically framed sexual orientation in terms of effects of variation in fetal androgen signaling on sexual differentiation, although other biological models exist. Despite marked sex differences in facial structure, the relationship between sexual orientation and facial structure is understudied. A total of 52 lesbian women, 134 heterosexual women, 77 gay men, and 127 heterosexual men were recruited at a Canadian campus and various Canadian Pride and sexuality events.

Consensual Nonmonogamy: Psychological Well-Being and Relationship Quality Correlates.

Consensually nonmonogamous relationships are those in which all partners explicitly agree that each partner may have romantic or sexual relationships with others (Conley, Ziegler, Moors, Matsick, & Valentine, 2013 ). In this article, research examining the associations between consensual nonmonogamy, psychological well-being, and relationship quality is reviewed. Specifically, three types of consensual nonmonogamy are examined: swinging, open relationships (including sexually open marriage and gay open relationships), and polyamory.

Psychopathic Sexuality: The Thin Line Between Fantasy and Reality.

In two studies, we explored the relations between psychopathic traits and sexual fantasy content. In Study 1, we rated content themes in the fantasy narratives of 195 men and women recruited at a Canadian university. In Study 2, we administered a sexual fantasy questionnaire to a sample of 355 Canadian undergraduate students.

Object of desire self-consciousness theory.

In this article, the authors discuss the construct of object of desire self-consciousness, the perception that one is romantically and sexually desirable in another's eyes. The authors discuss the nature of the construct, variations in its expression, and how it may function as part of a self-schemata or script related to romance and sexuality. The authors suggest that object of desire self-consciousness may be an adaptive, evolved psychological mechanism allowing sexual and romantic tactics suitable to one's mate value.

Physical size and sexual orientation: Analysis of the Chinese health and family life survey.

In the present study, the relationship between physical size and sexual orientation was examined. Participants were men and women comprising the Chinese Health and Family Life Survey (N > 3,500), which employed a national probability sample from China. This survey is important because no research has examined these issues in a representative, non-Western sample.

Asexuality and autochorissexualism (identity-less sexuality).

I present evidence that target-oriented paraphilias may occur in some who report no sexual attraction for others or those who identify as asexual. One target-oriented paraphilia in some asexual people is a disconnection between their identity and a sexual target/object. I name this phenomenon autochorissexualism or "identity-less" sexuality.

Sexual orientation, fraternal birth order, and the maternal immune hypothesis: a review.

In 1996, psychologists Ray Blanchard and Anthony Bogaert found evidence that gay men have a greater number of older brothers than do heterosexual men. This "fraternal birth order" (FBO) effect has been replicated numerous times, including in non-Western samples. More recently, strong evidence has been found that the FBO effect is of prenatal origin.

On the association between sexual attraction and adolescent risk behavior involvement: Examining mediation and moderation.

On the basis of a large-scale survey of high-school youth, the authors compared adolescents reporting exclusively heterosexual, mostly heterosexual, bisexual, and predominately same-sex attraction based on high-risk involvement across a range of risk behaviors. Bisexual and same-sex attracted groups were characterized by heightened high-risk involvement relative to the other two groups. Mediation analysis was used to determine whether these group disparities were explained by a set of normative predictive factors spanning multiple life domains.

Interaction of birth order, handedness, and sexual orientation in the Kinsey interview data.

Recent evidence indicates that 2 of the most consistently observed correlates of men's sexual orientation--handedness and older brothers--may be linked interactively in their prediction of men's sexual orientation. In this article, the authors studied the relationship among handedness, older brothers, and men's sexual orientation in the large and historically significant database originally compiled by Alfred C. Kinsey and his colleagues (A.