Is There A Gay Gene?

EVANSTON, ILLINOIS - One of the great mysteries of human sexuality is what causes some men to be gay.
Scientists have rejected earlier notions that homosexuality is a mental illness. The thinking now is that sexual orientation is determined by roughly 40 percent genetic factors and 60 percent environmental factors.
And now researchers at Evanston Northwestern Healthcare Research Institute are hoping to identify one or more genes that help determine sexual orientation.
The Molecular Genetic Study of Sexual Orientation is recruiting 1,000 pairs of gay brothers to donate blood samples for DNA analysis.
"We hope our study will dispel mythologies and ignorance about homosexuality," said Dr. Alan Sanders, a Northwestern University psychiatrist who is directing the five-year study.
Some fear tests, 'cure'
If science can show that homosexuality is a biological trait, like eye color, the public likely would be more accepting of gays, said Timothy Murphy, a University of Illinois at Chicago bioethicist and paid consultant to the study.
But some gays are wary. They fear discovering gay genes could lead to efforts to "cure" homosexuality, or to prenatal tests for gay genes.
Researchers say that's not their intent.
Also wary of genetics research, Murphy said, are religious conservatives who believe homosexuality is a lifestyle choice.
But Greg and Phil Scollan of Chicago, two gay brothers who are participating in the study, believe there could be benefits to the research. It might "make people re-evaluate their thoughts on homosexuality," Phil Scollan said.
Tends to run in families
Homosexuality tends to run in families. While 2 percent to 4 percent of all men are gay, 8 percent to 12 percent of brothers of gay men are gay.
Previous twin studies have pointed to both genetic and environmental causes. An identical twin who is gay is much more likely to have a gay twin than is a fraternal twin who is gay. But even though identical twins share the exact same genes, it's not unusual for one twin to be gay and the other twin to be straight.
Possible environmental factors include family upbringing, exposure to certain hormones during pregnancy and having older brothers.
from The Chicago Sun-Times