This article, published in 1993, affirms what many have always suspected. So
what does that mean? It means "Leave these poor people alone!". People can
not help how they were born, only how they act.

http://www.pbs.org/wgbh/aso/databank/entries/dh93ge.html

A self-proclaimed "obscure molecular geneticist," Dean Hamer, had conducted
a study in the early 1990s that showed a correlation of a DNA marker on the
X chromosome with homosexual men that was higher than random distribution
would have been. The study had looked at extended family histories and at
the DNA of gay men. Researchers found that a tiny portion of the X
chromosome appeared the same in a surpringly high proportion of gay
brothers. Hamer's team did not find a so-called gay gene, but found evidence
to suggest such a thing existed. The results were printed in the journal
Science in June, 1993, sparking headlines that ranged from seriousness to
tabloid silliness.

The article appeared just as President Clinton was pushing for a new policy
of tolerance of homosexual people in the armed services. What Hamer, and
many others, found was the fact that "the genetics of behavior, and
sexuality in particular, is an emotionally and politically charged topic."

Equally as controversial are discussions of genes for intelligence. The X
chromosome has helped reveal genes linked to intellectual activity, sparked
by the discovery of fragile-X syndrome, the most common form of mental
retardation. After Down's syndrome it is the most frequently occurring
inherited disease among Westerners. The gene sequence causing fragile-X has
been identified, though not entirely understood. It is not an intelligence
gene, but one that controls fetal development. Down's syndrome, too, is
revealing of the role of genes in development of intellect: most Down's
syndrome children are born with an extra copy of one chromosome. This
difference amounts to less than 2 percent of the chromosome count, but
causes gross impairment of intellect as well as physiological problems. Abou
t half of the 50-100 thousand genes individuals inherit from their parents
are thought to be involved in brain development. But "nature" is only part
of the picture, and its countless twists, turns, and variations make human
development far from straightforward.

Advances in the understanding of Alzheimer's disease have helped push
discoveries in the relationship of genes and behavior. As with heart
disease, a person may have a gene that predisposes him or her to develop
symptoms. In some cases the symptoms will occur regardless of behavior, but
in most cases there are environmental or "lifestyle" influences that spur
development of the disease. Eating fatty foods can cause arteriosclerosis,
and drinking lots of aluminum-rich water can cause buildup of amyloid in the
brain, a physical cause of Alzheimer's dementia.

The genetic link to a homosexuality and the pursuit of knowledge about each
and every human gene has raised ethical and practical questions about
searching for genes for violence or aggression, shyness, intelligence, and
other behaviors.