Genetics can have an impact on sexual preference

milkboys News & Articles 3 Comments

The findings of what is being touted as the largest-ever study of the role genetics plays in same-sex sexual behaviour found that genetics plays about a third of the influence on whether someone has same-sex sex but there’s no single “gay gene,” the New York Times and many other outlets reported last week citing findings published in the journal Science.

The influence comes not from one gene but many, each with a tiny effect — and the rest of the explanation includes social or environmental factors — making it impossible to use genes to predict someone’s sexual orientation, the Times reports.

The study of nearly half a million people, funded by the National Institutes of Health and other agencies, found differences in the genetic details of same-sex behaviour in men and women. The research also suggests the genetics of same-sex sexual behaviour shares some correlation with genes involved in some mental health issues and personality traits — although the authors said that overlap could simply reflect the stress of enduring societal prejudice, the Times reports.

The study analysed the genetic data of 408,000 men and women from a large British database, the U.K. Biobank, who answered extensive health and behaviour questions between 2006-2010, when they were between the ages of 40-69. The researchers also used data from nearly 70,000 customers of the genetic testing service 23andMe, who were 51 years old on average, mostly American, and had answered survey questions about sexual orientation. All were of white European descent, one of several factors that the authors note limit their study’s generalisability. Trans people were not included, the Times reports.

The researchers mainly focused on answers to one question: whether someone ever had sex with a same-sex partner, even once.

A much higher proportion of the 23andMe sample — about 19 percent compared to about 3 percent of the Biobank sample — reported a same-sex sexual experience, a difference possibly related to cultural factors or because the specific 23andMe sexual orientation survey might attract more LGB participants, the Times reports.

Despite its limitations, the research was much larger and more varied than previous studies, which generally focused on gay men, often those who were twins or were otherwise related.

There might be thousands of genes influencing same-sex sexual behaviour, each playing a small role, scientists believe. The new study found that all genetic effects likely account for about 32 percent of whether someone will have same-sex sex, the Times reports.

Using a big-data technique called genome-wide association, the researchers estimated that common genetic variants — single-letter differences in DNA sequences — account for between 8 percent and 25 percent of same-sex sexual behaviour. The rest of the 32 percent might involve genetic effects they could not measure, they said.

Comments 3

  1. Its “limitations”? Its flaws, rather: I have no confidence in a study that claims only 3% of Brits are gay. ;)

    All the study says is that some gays share some common genes that the majority of gays don’t even have. We have also known for many years that there are no gay genes, the genetic model has flaws such as for identical twins that discredit it.

    The study reports on 2 sites in the genomes that a third of all gays have in common. There are 2 more genetic sites for male gays only, and one for females. But these 2 other sites make males who have them “only 0.4% more likely to engage in homosexual activity.” And the heterosexual males who have occasional homosexual relationships and who also have all 3 or 4 “gay” genetic sites don’t have more same sex relationships than the ones who have only 1 or 2.

    Also, the survey was only about sexual behavior. Hopefully, there is some overlap between sexual behavior and sexual orientation, but the Political Posts in this blog remind us that it is not always the case.

    So far, the only sexual orientation model that works is about epigenetic markers, not genetics, an environmental determination. Environmental in genetics means biological influence in the immediate vicinity (environment) of the genes, not social or educational environment.
    These epigenetic markers don’t change our genetic make-up, our DNA, but they can control if a specific gene will be activated or disabled, producing a specific protein or not.
    Now, what this actually does to the body or rather the brain, since sexual orientation is not a property of the heart or the dick, we still don’t know.

  2. Milkboys (or rather NYT) does a better job at reporting this story than many news papers, though it still mixes up sexual preferences from sexual activities. Some heterosexual people have had same sex sex whereas some homosexual people haven’t had it. This means the study will underestimate the hereditary part of sexual preferences.

    Also, if they want a model that captures a larger chunk of those 32 % (which as stated is probably too low) they can’t just study genes individually and add the effects. They probably need an artificial neural network or some other machine learning algorithm.

Leave a Comment