Study shows, Male sexual orientation influenced by genes

A study of gay men in the US has found fresh evidence that male sexual orientation is influenced by genes. Scientists tested the DNA of 400 gay men and found that genes on at least two chromosomes affected whether a man was gay or straight.
A region of the X chromosome called Xq28 had some impact on men's sexual behaviour – though scientists have no idea which of the many genes in the region are involved, nor how many lie elsewhere in the genome.
Another stretch of DNA on chromosome 8 also played a role in male sexual orientation – though again the precise mechanism is unclear.
Researchers have speculated in the past that genes linked to homosexuality in men may have survived evolution because they happened to make women who carried them more fertile. This may be the case for genes in the Xq28 region, as the X chromosome is passed down to men exclusively from their mothers.