Why would anyone choose to become a homosexual, willing to face the wrath and scorn of family and society? Is this sexual preference a lifestyle choice, as we now refer to it, or a deviant moral perversion?

It's neither, according to a paper just published in the April '95 issue of Archives of Sexual Behavior. The study, by Dr. William J. Turner, a Professor Emeritus of Psychiatry at the State University of New York at Stony Brook, links homosexual behavior to a DNA sequence at a specific location on the long arm of the X chromosome.

The genetic study, conducted over a period of six years, began when it was discovered that there was an unusually low ratio of uncles in the families of the mothers of gay children. In interviews of the families of 118 homosexual men, there were only 210 uncles to 320 aunts, rather than the usual one male for every female ratio that is found in the general population.

Evidence shows that 30% of the males conceived in the maternal generation do not survive long enough to be born. Among the mother's relatives there occur, far more frequently than in the father's relatives, such biologically-determined events as gay and lesbian siblings and cousins, infertility of male and female relatives, multiple miscarriages, failure to marry, and suicide.

Further evidence shows that the exact same ratio of uncles to aunts that is found in the families of homosexuals can be found in 9 other well-established X-chromosomal conditions, such as color blindness, a form of hemophilia, and a rare muscular disability.

What happens on the genetic level to cause homosexuality? According to Dr. Turner, there is a gene or genes on the X and Y chromosomes that give rise to our usual heterosexuality. The gene or genes in question may be inactivated by a specific sequence of DNA called trinucleotide repeats. An example of this is the DNA sequence consisting of one cytosine and two guanines. When the number of repeats are no greater than 40, the gene is activated normally.

Sequences containing the nucleotide cytosine are unique. Cytosine is the only nucleotide which can undergo a reaction called "methylation," a process whereby S-adenosyl methionine gives methyl ions to cytosine, transforming it into thymine, a new nucleotide. The longer the chain of repeats, and the greater the methylation, the more the heterosexual gene will be inactivated.

If the number of repeats is too great, then it would be lethal, which explains why so many males of the mother's generation die before birth.

So, homosexuality is transmitted through mothers to sons and daughters, not by overprotective or seductive behavior, as was once believed, but what Dr. Turner calls the ‘Gene for Gender’, the Xq28 region of her chromosomes.

"Homosexuals should not be accused of being sinful or willfully contrary," said Dr. Turner. "It is a natural occurrence much like being born with brown or blonde hair." Dr. Turner added that "since homosexuality has a worldwide occurrence of about five percent of all populations, perhaps its existence plays some important role in the survival of populations."

Dr. Turner is currently examining the extraordinary relationship of the gradation of this genetic phenomenon to the full spectrum of sexual behavior/preference including asexuals, bisexuals, transvestites and transsexuals.