How many identical twins are both gay

Perkins, M. Homosexuality in female monozygotic twins. Puterbaugh, G. In Puterbaugh, G. Rainer, J. Homosexuality and heterosexuality in identical twins. Schlegel, W. Die Konstitutionsbiologischen Grundagen der Homosexualitat.

Konstitutiotnslehre — Whitam, F. The sexual orientation of homosexual twins. A preliminary report on the sexual orientation of homosexual twins. The sexual fantasies of male homosexual twins. Zuger, B. Monozygotic twins discordant for homosexuality: Report on a pair and significance of the phenomenon.

Download references. Frederick L. Whitam Ph. You can also search for this author in PubMed Google Scholar. Reprints and Permissions. Homosexual orientation in twins: A report on 61 pairs and three triplet sets. Arch Sex Behav 22, — Download citation. Issue Date : June Anyone you share the following link with will be able to read this content:.

Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search SpringerLink Search. Homosexuality as a consequence of epigenetically canalized sexual development. Sexually antagonistic epigenetic marks that canalize sexually dimorphic development. Blanchard, R. Fraternal birth order, family size, and male homosexuality: Meta-analysis of studies spanning 25 Years.

Response to commentaries: Meta-analysis of probability samples and other new evidence. Bogaert, A. Proceedings of the National Academy of Sciences , In Contemporary perspectives on lesbian, gay, and bisexual identities Vol. Debra, A. Hope 43—63 Springer, Janssen, E. Whitley, Jr. Suschinsky, K. Sex differences in patterns of genital sexual arousal: Measurement artifacts or true phenomena? Genetic and environmental influences on sexual orientation and its correlates in an Australian twin sample.

Price, T. Infant zygosity can be assigned by parental report questionnaire data. Article Google Scholar. Sexual arousal patterns of bisexual men. Watts, T. Pupil dilation to explicit and non-explicit sexual stimuli. Little, R. Statistical analysis with missing data. Download references. We thank Joan A. Linsenmeier and J. Michael Bailey for their support and advice.

Tuesday M. You can also search for this author in PubMed Google Scholar. The experiment was conceived by T. Data were collected by T. The manuscript text was written by T. Correspondence to Gerulf Rieger. Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Reprints and Permissions. Sci Rep 8, Download citation. Received : 02 January Accepted : 25 September Published : 08 October Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Archives of Sexual Behavior By submitting a comment you agree to abide by our Terms and Community Guidelines.

If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate. Advanced search. Skip to main content Thank you for visiting nature. Download PDF. Subjects Human behaviour Reproductive biology. Abstract Genetically identical twins can differ in their self-reported sexual orientations.

Introduction A recent review of twin studies indicates that although both genetic variations and the non-shared environment contribute to population-level differences in sexual orientation, the contribution of the non-shared environment is much stronger 1. Results Sexual Arousal of Male Twins We predicted that heterosexual male twins show stronger sexual responses to the other sex, whereas their homosexual co-twins respond more strongly to the same sex.

Figure 1. Full size image. Figure 2. Figure 3. Figure 4. Discussion The present study suggests that identical twins with discordant self-reported sexual orientations differ in their patterns of physiological sexual arousal in a manner similar to unrelated heterosexual and homosexual individuals.

Participants Twins We advertised for identical twins with discordant sexual orientations via newsletters at UK universities, social media sites, online news sites for gay men and lesbians, and at three gay Pride festivals. Unrelated participants Unrelated participants took part in previously conducted studies and included 94 heterosexual men, 97 homosexual men, 77 heterosexual women, and 44 homosexual women with genital arousal data, and heterosexual men, homosexual men, heterosexual women, and homosexual women with pupil data 5 , 6 , 8 , 33 , Material and Measures Stimuli Six 3-minute videos, three of which showed males and three showed females, were used as sexual stimuli.

Procedure Twins provided written informed consent and were seated in a dimly lit room facing a screen with resolution of by pixels. A growing amount of research suggests that sexual orientation has a genetic basis. In fact, scientists recently identified two specific genes that appear to differ between gay and straight men [1]. If sexual orientation is indeed genetically determined, it would be tempting to assume that identical twins would always have the same orientation, right?

If they have the exact same genes and our genes control our sexuality, this would seem like a pretty logical conclusion. Identical twins sometimes have different orientations. For example, one may be straight while the other is gay. So why is that? This idea has been refuted scientifically, though. In a study where scientists looked at the sexual arousal patterns of identical twins with different sexualities—specifically, where one was gay and the other was straight—they found that gay twins demonstrated more genital arousal in response to same-sex images, whereas straight twins demonstrated more arousal in response to opposite-sex images [2].

The field of epigenetics tells us that our genes interact with our environment, and that the environment is capable of turning specific genes on or off. What might those environmental factors be? So an international team of researchers, which I led, set out to tackle this problem. Our results are published today in Science. Our approach was simple: brute force. All else being equal, the larger a study, the more confident we can be in the results.

So instead of sampling a few hundred or a few thousand individuals — as in previous genetic studies on sexual preference — we used a sample of nearly half a million. To obtain such a large sample, we used data that had been collected as part of much broader projects.

These included DNA data and responses to questionnaires from participants in the UK as part of the UK Biobank study and the US as part of data collected from customers of the commercial ancestry firm 23andMe who consented to answering research questions about sexuality. The downside of using these huge data sets was that the studies were not specifically designed to find genes for sexual preference, so we were limited by the questions participants happened to have been asked about their sexual behaviour.

For both UK Biobank and 23andMe, participants reported whether they had ever had a same-sex sexual partner. So, to make a complicated story short, the next step was to test at every DNA location whether one letter was more common in participants who reported any same-sex partners than in those who reported only opposite-sex partners.

Individually, each of these genes has only a very small effect, but their combined effect is substantial.