Scientists Discover Epigenetics May Be Responsible for Homosexuality

Theories of Causes of Homosexuality

Homosexuality used to be thought of as a result of a domineering mother and an ineffectual father.  Religious zealots still believe it’s a “choice” of  a “gay lifestyle.”  The hereditary link has been established, but because of twins’ studies, scientists knew it wasn’t just a genetic link. In identical twins, there’s about a 20 percent chance that if one twin is gay, the other will be too. If genetic change were responsible for homosexuality, you’d expect a much higher match.

Scientists Have New Theory Why Homosexuality May Run in Families

The new study, published by William R. Rice, Urban Friberg, and Sergey Gavrilets.  Homosexuality as a Consequence of Epigenetically Canalized Sexual Development.  Review of Biology, 2012%3B 87 (4)The Quarterly Review of Biology, December 11, 2012, concludes that epigenetics that switches genes on and off may explain why homosexuality is passed on in families.

Here’s How It Works

The gene expression is regulated by temporary switches called epi-marks.  They constitute an extra layer of information attached to our genes’ backbones that regulates their expression. Epi-marks direct when, where, and how much a gene is expressed during development.

Different epi-marks protect different sex-specific traits from being masculinized or feminized – some affect the genitals, sexual identity or sexual partner preference. They protect fathers and mothers from excess or underexposure to testosterone.

These epi-marks are usually erased between generations.  However, they can cause reverse effects when the epi-marks are transmitted across generations from fathers to daughters or mothers to sons, resulting in feminization of some traits in sons, such as sexual preference, and similarly a partial masculinization of daughters.

More Study Needed

In the current study, researchers produced and biological and mathematical model that delineates the role of epigenetics in homosexuality.  William Rice, lead author of the study and evolutionary biologist at the University of California Santa Barbara, says that “these findings could explain why twin studies show that homosexuality runs in families, but no “gay gene” can be found.  Epigenetics, however, can explain the heritability without the need for a specific genetic change.”

The hypothesis could be tested by examining epigenetic marks in real-life parents-offspring pairs. There’s more verification needed, and epigenetic profiles genome-wide. Other studies are needed to look at epi-marks empirically.  This can be tested and proven within six months.

Additional Moral Concerns

Rice added “that an understanding of the biological underpinnings of homosexuality could help emphasize that same-sex behavior is not ‘unnatural.’ We think that people who are gay or lesbian have the right to know, what is the biological foundation for this condition?”


Conservatives like Bryan Fischer, Host of  the nationally syndicated Christian radio show “Focal Point,” and Director of Issues and Analysis for the American Family Association, are already concerned that if homosexuality is rooted in physical causes – what he terms “genetic defect”- that this discovery may lead parents to abort gay children.