Gays don't chose to be gay, any more than the rest of choose to be hetero.
Yes, NOYB. BS. Biological Science.
Even if you want to call it a choice, there are common variations of the X
chromosone among male homosexuals who make that choice. And no, all those PhD's
at the end of this piece do not stand for "practicing homosexual doctor".
What is rather interesting is that this information evolved from a genetic
study of men who had died from AIDS. There was no predetermined objective to
prove anything about genetics and homosexual behavior, that turned out to be an
Read and learn:
National Cancer Institute
National Institutes of Health
A new study has found a correlation between a specific region of the X
chromosome and male homosexuality. The finding represents new evidence that
sexual orientation may be influenced by heredity.
The study is reported in the July 16 issue of Science by scientists from the
National Institutes of Health in Bethesda, Maryland.
By analyzing the inheritance of genetic markers in pairs of homosexual
brothers, the scientists localized the region related to sexual orientation to
a minute segment of the human genome. However, a specific gene has not yet been
Dean Hamer, Ph.D., chief author of the study, said, "The region that we've
discovered represents a significant variation in the human genetic repertoire.
If the gene itself can be isolated, then it will be important to understand how
it interacts with other genes, the brain, and the environment to influence a
trait as complex and variable as human sexuality."
Hamer is with the National Cancer Institute and conducted the study as part of
the Institute's effort to identify genetic factors involved in cancers that are
frequently found in gay men infected with the AIDS virus.
Hamer and colleagues studied the family histories of 114 gay men and found that
their brothers, maternal uncles, and maternal male cousins were more likely to
be homosexual than would be expected among the general male population. In some
families, gay relatives could be traced back for three generations. Because the
homosexual uncles and male cousins of the gay subjects were raised in different
households, the scientists hypothesized that a genetic factor was involved.
Furthermore, the maternal link suggested that homosexuality might be associated
with the X chromosome, which is the sex-linked chromosome that men inherit only
from their mothers.
Explicit evidence for a genetic link was obtained by studying the X chromosome
DNA of 40 pairs of gay brothers. The scientists used a technique called linkage
mapping to search for patterns of similarity in the genetic information of
related individuals. Thirty-three of the gay sibling pairs had coinherited
genetic markers in the same chromosome region called Xq28, suggesting that 65
percent of the families studied were transmitting a gene for homosexual
"The statistical significance of the results was better than 99 percent, which
means that the possibility of obtaining our findings by chance is extremely
unlikely," said Hamer. However, he noted that replication on an independent
population of families will be necessary to confirm the results.
The scientists do not know why 7 of the 40 pairs of gay brothers did not
coinherit the Xq28 genetic marker. Hamer postulated that these gay men may have
inherited other genes that are associated with homosexuality, or they might
have been influenced by environmental factors or life experiences.
"Given the intricacies of human behavior, it is not surprising that a single
genetic locus [region] fails to account for all of the variation seen in the
study group," said Hamer. "What is remarkable is that we can account for at
least some of the inherited variability with a fair degree of statistical
The scientists are also studying the families of lesbians. Preliminary results
suggest that female sexual orientation is genetically influenced, but DNA
markers have not been detected yet.
Hamer emphasized that the study was not designed to test for sexual
orientation. The findings do not permit determination of an individual's sexual
orientation, he pointed out, because the complexities of sexuality cannot be
fully explained by a gene or genes.
As efforts to map the human genome progress, there will be increasing concern
about how the information is used. Scientists, educators, policymakers, and the
public should work together to ensure that behavioral genetics research is used
to benefit all members of society and not to discriminate," said Hamer.
The study is titled "A Linkage Between DNA Markers on the X Chromosome and Male
Sexual Orientation." The authors are Dean H. Hamer, Ph.D., Stella Hu, M.A.,
Victoria L. Magnuson, Ph.D., Nan Hu, M.D., and Angela M. L. Pattatucci, Ph.D.