Our findings should not in any way be interpreted so as to imply that the experiences of LGBTQ individuals are “wrong” or “disordered.” In fact, this study provides further evidence that diverse sexual behavior is a natural part of overall human variation. Our research is intended to improve our understanding of the genetic basis of same-sex sexual behavior. It should not be misconstrued to disparage LGBTQ people.

Previous studies have found strong evidence that same-sex sexual behavior is partly heritable, meaning that same-sex sexual behavior is influenced, in part, by genetic variants. Studies of same-sex sexual behavior in twins show (READ MORE)

Previous studies have found strong evidence that same-sex sexual behavior is partly heritable, meaning that same-sex sexual behavior is influenced, in part, by genetic variants. Studies of same-sex sexual behavior in twins show that the heritability is between 30 and 40 percent. This level of heritability is similar to other behavioral and personality traits, such as extroversion or how many years someone spends in school. Heritability is a population statistic rather than an individual one, and a heritability of 30% does not mean that each individual has a 30% contribution of genetic factors for same-sex sexual behavior. These numbers are based on population estimates and probability and therefore cannot be used to make deterministic claims about whether someone will engage in same-sex sexual behavior or express any particular sexual identity. (For more, see Kendler; Kirk and Långström).

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We also know that genetics is not the only factor influencing sexual behavior, identity, or orientation; Human sexuality, like other human traits, is influenced by a complex mix of genetic factors, environmental influences, and life experiences (READ MORE)

We also know that genetics is not the only factor influencing sexual behavior, identity, or orientation. Human sexuality, like other human traits, is influenced by a complex mix of genetic factors, environmental influences, and life experiences. If you are interested in learning more about these non-genetic influences, or if you are having questions about your own sexual identity, we encourage you to visit websites that provide more general information about sexual orientation (e.g., The Human Rights Campaign, The Trevor Project, The Association of LGBTQ Psychiatrists, The LGBT National Help Center, GLAAD, Mental Help America (LGBT Communities and Mental Health), The National Alliance on Mental Health- LGBTQ, The World Health Organization: Gender, Equity, Human Rights/Sexual Health and Diversity,  PFLAG.org, American Psychological Association, GLMA and Lambda Legal).

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The aim of our study was to use genetic information to better understand same-sex sexual behavior. This is a largely understudied area of scientific research, and we have unique opportunities to contribute to the field. Our goals were to:

  1. Find genetic markers associated with same-sex sexual behavior, so that we can try to understand the processes involved in the development of this behavior. We estimated how much the differences between people’s sexual behavior could be explained by DNA markers, and whether the genetic effects differed between females and males.
  2. Examine biological pathways that might be associated with same-sex sexual behavior.
  3. Better understand the complexity of sexual orientation by exploring genetic differences between females and males; between behavior, attraction, and identity; and between different sexual behaviors.
  4. Estimate the extent to which genetic variants associated with same-sex sexual behavior have also been associated with personality, reproductive health, and mental health. For instance, as we elaborate here (point #5), LGBTQ individuals are at higher risk for physical and mental health conditions, likely due to experiences of discrimination and marginalization. Further study into these health disparities in relation to LGBTQ individuals is needed in order to protect vulnerable community members.

To answer these questions, we analyzed existing information from nearly half a million research participants to explore many questions about genetics and human health. We looked at information about how people self-reported their sexual history and compared it with millions of DNA markers across these individuals’ genomes to find markers that were associated with same-sex sexual behavior. Importantly, since we were working with existing information, we were limited by the demographic data captured by these datasets, as we explain here.

Ours is not the first study to look for genetic markers of same-sex sexual behavior or orientation. However, (READ MORE)

Ours is not the first study to look for genetic markers of same-sex sexual behavior or orientation. However, past studies had too few people participating and often looked at too few DNA markers to draw any reliable and reproducible conclusions. By incorporating DNA and personal information from nearly half a million people, our study is the first to include enough people to be able to link specific genetic variants and same-sex sexual behavior with demonstrable statistical confidence.

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