Family and Sexual Orientation: The Family-Demographic Correlates of Homosexuality in Men and Women

  title={Family and Sexual Orientation: The Family-Demographic Correlates of Homosexuality in Men and Women},
  author={Andrew M. Francis},
  journal={The Journal of Sex Research},
  pages={371 - 377}
Using a nationally representative sample of young adults, I identify the family-demographic correlates of sexual orientation in men and women. Hence, I test the maternal immune hypothesis, which posits that the only biodemographic correlate of male homosexuality is the number of older brothers, and there are no biodemographic correlates of female homosexuality. For men, I find that having one older brother does not raise the likelihood of homosexuality. Although having multiple older brothers… 

Fraternal Birth Order, Family Size, and Male Homosexuality: Meta-Analysis of Studies Spanning 25 Years

The fraternal birth order effect is the tendency for older brothers to increase the odds of homosexuality in later-born males and in homosexual subjects with masculine versus feminine gender identities is compared and evidence for the reliability of the effect was consistent.

Detecting and Correcting for Family Size Differences in the Study of Sexual Orientation and Fraternal Birth Order

Two fraternal birth order studies published in the last 5 years were surveyed for failures to find a statistically significant excess of older brothers for the homosexual group and suggested that the mean family size of the homosexual groups was smaller than that of the heterosexual comparison groups.

Birth Order and Sibling Sex Ratio of Children and Adolescents Referred to a Gender Identity Service

The greater frequency of only children and elevated numbers of older sisters among the homosexual female group adds to a small literature on sibship characteristics of potential relevance to the development of gender identity and sexual orientation in females.

The Effect of Religious Background on Sexual Orientation

Does religious background influence sexual orientation? Research on the etiology of sexual orientation has focused almost exclusively on biological influences; however, the evidence suggests that

Birth weight and two possible types of maternal effects on male sexual orientation: a clinical study of children and adolescents referred to a Gender Identity Service.

Findings support the existence of two maternal immune responses influencing male sexual orientation and possibly also cross-gender behavior and identity.

Gender Nonconformity and Birth Order in Relation to Anal Sex Role Among Gay Men

The results suggest that the fraternal birth order effect may apply to a subset of gay men who have a bottom anal sex role preference and that this subgroup is more gender-nonconforming, but there were no significant associations between fraternalBirth order and gender nonconformity at the individual level.

Multiple Aspects of Sexual Orientation: Prevalence and Sociodemographic Correlates in a New Zealand National Survey

Heterosexuals were more likely than bisexuals or homosexuals to have ever married or had biological children, with differences more marked for males than for females.

Handedness and Birth Order Among Heterosexual Men, Gay Men, and Sao Praphet Song in Northern Thailand.

Sexual orientation and gender identity simultaneously is investigated simultaneously via comparison of 282 heterosexual men, 201 gay men, and 178 sao praphet song-i.e., androphilic, markedly feminine males recognized as a "third" gender in Thailand to provide new insights and replicate previous findings in a non-Western sample.


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Sexual Orientation and Labor Force Participation: Findings from Chile and Uruguay

ABSTRACT This is the first study that examines the association between sexual orientation and labor force participation in Chile and Uruguay. Using information on heads of households and their




Results are consistent with the hypothesis that the high birth order of homosexual men reflects the progressive immunization of certain mothers to H-Y antigen by succeeding male fetuses, and the increasing effects of H- Y antibodies on sexual differentiation of the brain in succeeding male Fetuses.

Homosexuality in men and number of older brothers.

The range of possible theories of the birth order phenomenon is restricted to those that can explain not only why older brothers increase the probability of homosexuality in later-born males but also why older sisters neither enhance this effect nor counteract it.

Evidence of familial nature of male homosexuality.

There is a significant familial component to male homosexuality, with heterosexual index men having about as many homosexual brothers as would be predicted given national prevalence figures for homosexuality, but homosexual index men had about four times as many gay brothers, although in both cases most brothers were heterosexual.

Sibship Size, Sibling Sex Ratio, Birth Order, and Parental Age in Homosexual and Nonhomosexual Gender Dysphorics

The results concerning sibling sex ratio and birth order are consistent with previous findings for homosexual men.

A genetic study of male sexual orientation.

Homosexual male probands with monozygotic cotwins, dizygotic cotwins, or adoptive brothers were recruited using homophile publications. Sexual orientation of relatives was assessed either by asking

The economics of sexuality: the effect of HIV/AIDS on homosexual behavior in the United States.

Fraternal Birth Order and the Maternal Immune Hypothesis of Male Homosexuality

The maternal immune hypothesis is consistent with a variety of evidence, including the apparent irrelevance of older sisters to the sexual orientation of later born males, the probable involvement of H-Y antigen in the development of sex-typical traits, and the detrimental effects of immunization of female mice to H-y antigen on the reproductive performance of subsequent male offspring.

Biological versus nonbiological older brothers and men's sexual orientation.

  • A. Bogaert
  • Psychology
    Proceedings of the National Academy of Sciences of the United States of America
  • 2006
A direct test pitting prenatal against postnatal mechanisms strongly suggests a prenatal origin to the fraternal birth-order effect in men, regardless of the amount of time reared with these siblings.

The Social Organization of Sexuality: Sexual Practices in the United States

This survey of sexual practices in the United States has been combed by the media for items of interest to the public: monogamous sex is much more widespread in this country than has been thought;