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Concept: Heterosexuality

905

We show that easily accessible digital records of behavior, Facebook Likes, can be used to automatically and accurately predict a range of highly sensitive personal attributes including: sexual orientation, ethnicity, religious and political views, personality traits, intelligence, happiness, use of addictive substances, parental separation, age, and gender. The analysis presented is based on a dataset of over 58,000 volunteers who provided their Facebook Likes, detailed demographic profiles, and the results of several psychometric tests. The proposed model uses dimensionality reduction for preprocessing the Likes data, which are then entered into logistic/linear regression to predict individual psychodemographic profiles from Likes. The model correctly discriminates between homosexual and heterosexual men in 88% of cases, African Americans and Caucasian Americans in 95% of cases, and between Democrat and Republican in 85% of cases. For the personality trait “Openness,” prediction accuracy is close to the test-retest accuracy of a standard personality test. We give examples of associations between attributes and Likes and discuss implications for online personalization and privacy.

Concepts: Psychology, Personality psychology, White American, Sexual orientation, African American, Neuroticism, Trait theory, Heterosexuality

185

A variety of social, developmental, biological and genetic factors influence sexual orientation in males. Thus, several hypotheses have attempted to explain the sustenance of genetic factors that influence male homosexuality, despite decreased fecundity within the homosexuals. Kin selection, the existence of maternal effects and two forms of balancing selection, sexually antagonistic selection and overdominance, have been proposed as compensatory mechanisms for reduced homosexual fecundity. Here, we suggest that the empirical support for kin selection and maternal effects cannot account for the low universal frequency and stability of the distribution of homosexuals. To identify the responsible compensatory mechanism, we analyzed fecundity in 2,100 European female relatives, i.e., aunts and grandmothers, of either homosexual or heterosexual probands who were matched in terms of age, culture and sampling strategy. Female relatives were chosen to avoid the sampling bias of the fraternal birth order effect, which occurs when indirectly sampling mothers though their homosexual sons. We observed that the maternal aunts and grandmothers of homosexual probands were significantly more fecund compared with the maternal aunts and maternal grandmothers of the heterosexual probands. No difference in fecundity was observed in the paternal female lines (grandmothers or aunts) from either of the two proband groups. Moreover, due to the selective increase in maternal female fecundity, the total female fecundity was significantly higher in homosexual than heterosexual probands, thus compensating for the reduced fecundity of homosexuals. Altogether, these data support an X-linked multi-locus sexually antagonistic hypothesis rather than an autosomal multi-locus overdominance hypothesis.

Concepts: Scientific method, Gender, Sexual orientation, Homosexuality, Bisexuality, Heterosexuality

164

Many previous studies have reported robust sex differences in olfactory perception. However, both men and women can be expected to vary in the degree to which they exhibit olfactory performance considered typical of their own or the opposite sex. Sex-atypicality is often described in terms of childhood gender nonconformity, which, however, is not a perfect correlate of non-heterosexual orientation. Here we explored intrasexual variability in psychophysical olfactory performance in a sample of 156 individuals (83 non-heterosexual) and found the lowest odor identification scores in heterosexual men. However, when childhood gender nonconformity was entered in the model along with sexual orientation, better odor identification scores were exhibited by gender-nonconforming men, and greater olfactory sensitivity by gender-conforming women, irrespective of their sexual orientation. Thus, sex-atypicality, but not sexual orientation predicts olfactory performance, and we propose that this might not be limited to olfaction, but represent a more general phenomenon.

Concepts: Gender, Sense, Olfaction, Odor, Sexual orientation, Transgender, Olfactory fatigue, Heterosexuality

37

Studies of subjective and genital sexual arousal in monosexual (i.e. heterosexual and homosexual) men have repeatedly found that erotic stimuli depicting men’s preferred sex produce strong responses, whereas erotic stimuli depicting the other sex produce much weaker responses. Inconsistent results have previously been obtained in bisexual men, who have sometimes demonstrated distinctly bisexual responses, but other times demonstrated patterns more similar to those observed in monosexual men. We used fMRI to investigate neural correlates of responses to erotic pictures and videos in heterosexual, bisexual, and homosexual men, ages 25-50. Sixty participants were included in video analyses, and 62 were included in picture analyses. We focused on the ventral striatum (VS), due to its association with incentive motivation. Patterns were consistent with sexual orientation, with heterosexual and homosexual men showing female-favoring and male-favoring responses, respectively. Bisexual men tended to show less differentiation between male and female stimuli. Consistent patterns were observed in the whole brain, including the VS, and also in additional regions such as occipitotemporal, anterior cingulate, and orbitofrontal cortices. This study extends previous findings of gender-specific neural responses in monosexual men, and provides initial evidence for distinct brain activity patterns in bisexual men.

Concepts: LGBT, Sexual intercourse, Gender, Sexual orientation, Sexual arousal, Homosexuality, Bisexuality, Heterosexuality

28

Objectives. We examined purging for weight control, diet pill use, and obesity across sexual orientation identity and ethnicity groups. Methods. Anonymous survey data were analyzed from 24 591 high school students of diverse ethnicities in the federal Youth Risk Behavioral Surveillance System Survey in 2005 and 2007. Self-reported data were gathered on gender, ethnicity, sexual orientation identity, height, weight, and purging and diet pill use in the past 30 days. We used multivariable logistic regression to estimate odds of purging, diet pill use, and obesity associated with sexual orientation identity in gender-stratified models and examined for the presence of interactions between ethnicity and sexual orientation. Results. Lesbian, gay, and bisexual (LGB) identity was associated with substantially elevated odds of purging and diet pill use in both girls and boys (odds ratios [OR] range =  1.9-6.8). Bisexual girls and boys were also at elevated odds of obesity compared to same-gender heterosexuals (OR = 2.3 and 2.1, respectively). Conclusions. Interventions to reduce eating disorders and obesity that are appropriate for LGB youths of diverse ethnicities are urgently needed. (Am J Public Health. Published online ahead of print December 13, 2012: e1-e7. doi:10. 2105/AJPH.2012.301150).

Concepts: LGBT, Nutrition, Sexual orientation, Homosexuality, Bisexuality, Gay, Heterosexuality, Lesbian

27

Whereas women of all ages prefer slightly older sexual partners, men-regardless of their age-have a preference for women in their 20s. Earlier research has suggested that this difference between the sexes' age preferences is resolved according to women’s preferences. This research has not, however, sufficiently considered that the age range of considered partners might change over the life span. Here we investigated the age limits (youngest and oldest) of considered and actual sex partners in a population-based sample of 2,655 adults (aged 18-50 years). Over the investigated age span, women reported a narrower age range than men and women tended to prefer slightly older men. We also show that men’s age range widens as they get older: While they continue to consider sex with young women, men also consider sex with women their own age or older. Contrary to earlier suggestions, men’s sexual activity thus reflects also their own age range, although their potential interest in younger women is not likely converted into sexual activity. Compared to homosexual men, bisexual and heterosexual men were more unlikely to convert young preferences into actual behavior, supporting female-choice theory.

Concepts: Sexual intercourse, Gender, Sexual orientation, Transgender, Homosexuality, Bisexuality, Heterosexuality, Age of consent

27

The primary aim of this study was to investigate the relationship between gender role orientation and eating disorder attitudes and behaviors and body dissatisfaction in a sample of homosexuals, heterosexuals, and transsexuals.

Concepts: Gender, Gender role, Gender identity, Sexual orientation, Transgender, Masculinity, Gender studies, Heterosexuality

27

Emerging evidence from general population studies suggests that lesbian, gay, and bisexual (LGB) adults are more likely to experience adverse cardiovascular outcomes relative to heterosexuals. No studies have examined whether sexual orientation disparities exist in biomarkers of early cardiovascular disease risk.

Concepts: LGBT, Cardiovascular disease, Sexual orientation, Homosexuality, Bisexuality, Gay, Heterosexuality, Lesbian

27

Sexual minority (lesbian and gay, bisexual, mostly heterosexual) individuals are at an increased risk for hazardous drinking than heterosexual individuals, but little is known about the nature of the disparities as adolescents reach adulthood. We used four waves of a nationally representative data set, the National Longitudinal Study of Adolescent Health (Add Health), to examine disparities of hazardous drinking outcomes between sexual minority and heterosexual men and women from adolescence to young adulthood. Participants were 14-18 years old at the first assessment (N = 12,379; 53 % female) and 27-31 years old at the fourth assessment. At the fourth assessment, 13 % self-identified as sexual minority individuals, 16 % were Hispanic, and 36 % were of minority race, including primarily African Americans (60 %) and Asian Americans (18 %). There were clear hazardous drinking disparities between sexual minority individuals and heterosexual individuals over time. During adolescence, sexual minority individuals, particularly females, reported higher levels of hazardous drinking. As study participants reached adulthood, the magnitude of the hazardous drinking disparities increased among sexual minorities, sexual minority men in particular. Additional research is needed to better understand the developmental mechanisms that underlie the emerging sexual orientation related disparities of hazardous drinking in young adulthood.

Concepts: LGBT, United States, Sociology, Adolescence, Sexual orientation, Homosexuality, Bisexuality, Heterosexuality

25

Lesbian, gay, and bisexual (LGB) young people experience a variety of developmental trajectories that consist of milestones, the sequence and timing of which differ across individuals. They include early feelings of being different from peers, the onset of same-sex attraction, questioning one’s sexuality, first same-sex sexual experience, recognition and self-labelling, disclosure to others, first romantic relationship, and self-acceptance. The invention of ‘gay youth’ during the 1970s and 1980s is briefly reviewed with an emphasis on the ways in which the portrait created by early research fails to capture the developmental trajectories of millennial young people. Although some young people struggle with mental health problems as they navigate these milestones, research documents the complexity, variety, and normative nature of the vast majority of LGB young people. A growing chorus of developmental, behavioural, and social scientists now emphasize that many contemporary young people forego sexual confusion, recognize the sex or gender to which they are attracted to and love, and believe they are as mentally healthy as heterosexual young people.

Concepts: LGBT, Sexual orientation, Transgender, Homosexuality, Bisexuality, Gay, Heterosexuality, Lesbian