January 28, 2013

Research Suggests that Homosexuality Is Related to Epigenetics

A new study suggests that epigenetics may provide a clue to help solve the mystery of the origin of homosexuality.

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colorful double helix

colorful double helix

With the growing number of people coming out in the as gay, lesbian, and bisexual,  one of the questions commonly asked  is how does a person become homosexual? Is it a choice? Is it genetic? Recent research on epigenetics may or may not provide a piece to the puzzle that is the origin of homosexuality in individuals.

What Is Epigenetics?

Epigenetics is the study of changes in gene activity that do not involve changes to the genetic code, but still get passed down to at least one successive generation. Patterns of gene expression are governed by epigenomes, which are cellular material that “sit” outside of a gene. Epigenomes (also referred to as “epi-marks”) tell your genes to switch on or off, which controls how genes are expressed. Public Broadcasting Service puts it more simply by using the metaphor of the computer. Genes are the hard drive of the computer. They contain all of the information necessary for gene expression. Epigenomes are the software of the computer. They tell the genes what to do, which controls how each person’s genes are expressed.

How Does This Relate to Homosexuality?

Epi-marks are found on all of your genes, including the ones related to sexuality. A recent study published in The Quarterly Review of Biology by Rice, Friberg, and Gavrilets used mathematical modeling that found the transmission of sex-specific epi-marks may signal homosexuality. Very early on in the pregnancy, the fetus develops these sex-specific epi-marks to protect the fetus from receiving the wrong amount of testosterone. The epi-marks prevent a female fetus from becoming overly masculinized and a male fetus from becoming overly femininized.

There is not just one epi-mark that controls all sexual traits, however. Different epi-marks protect different sex-specific traits from being masculinized or feminized — some affect the genitals, others sexual identity, and still others affect sexual partner preference. The authors of this study state that though epi-marks are usually newly produced with each generation, recent evidence has shown that they sometimes carry over between generations. Sometimes when this happens, the child receives the traits of the opposite-sex parent. In the case of homosexuality, the son would receive the epi-mark for sexual preference from the mother and the daughter would receive the epi-mark for sexual preference from the father, which would cause them to be attracted to same-sex individuals.

Though other studies on this subject will have to be done to explore this initial hypothesis about the basis of sexual orientation, this study provides some preliminary research for this topic as we strive to gain more insight into sexual orientation as well as acceptance for homosexual and bisexual individuals.