Shocking claims from scientists reveal gay and straight men have different variations of at least two genes that somewhat correlate with their sexual orientation.

The human operating system is based on DNA structures one is born with. Now it looks like even sexual preferences are preprogrammed in the human operating system.

The Scientific Reports journal is reporting that scientists at the North Shore University in Illinois compared the genomes of 1,077 gay and 1,231 straight men from European origin.

They found differences in two genes.

One of those genes, coded SLITRK6, is responsible for brain development and the production of hormones. The other gene is TSHR. This one is responsible for the thyroid function, sexual preferences and weight loss.

Earlier studies have shown that the part of the brain where the SLITRK6 hormone is based, the hypothalamus region, is in gay men 34 % larger as in heterosexual men.

The TSHR gene has also something to do with the reproduction capability in woman. Woman with an irregular thyroid function often face severe difficulties getting pregnant.

Dr. Alan Sanders is one of the scientists involved in the study. He told reporters last week that the objective of this controversal study is to search for genetic underpinnings of male sexual orientation. At best it will increase the knowledge of biological mechanisms underlying sexual orientation.

Further he emphasized that “not all men who have the gay genes end up as a gay”

Again softening the findings: “It is understood that probably multiple genes are involved, each with a fairly low effect. There will be men who have the type of gene that increases the chance of being gay, but they won’t be gay”

The scientist warned that the findings are still not much more than speculative. Though they may pave the way for more conclusive studies.

Other researchers also expressed caution, as statistic studies usually involve a much larger and more diverse audience.

Since the study was carried out in European men, it is completely unknown what the result might be in non-European men or lesbian woman.

Scientific upheaval like this is not new. Genetic factors in sexual preferences are attracting scientist’s attention since 1993. It was the year of what reporters called, “The Gay Gene”

A variation discovered in the X chromosome between straight and gay men.

And the latest is another statistic outcome.

Men with an older brother are more likely to be homosexual then those who don’t.

For over two decades, the “Older Brother Effect” statistical study indicates that men who have an older brother are more likely to be gay than those without.