Homosexuality is only partly genetic with sexuality mostly based on environmental and social factors, scientists believe.
A study found that, while gay men shared similar genetic make-up, it only accounted for 40 per cent of the chance of a man being homosexual.
But scientists say it could still be possible to develop a test to find out if a baby was more likely to be gay.
In the most comprehensive study of its kind, Dr Michael Bailey, of Northwestern University, has been studying 400 sets of twins to determine if some men are genetically predisposed to being gay.
The study found that gay men shared genetic signatures on part of the X chromosome – Xq28.
Dr Bailey said: “Sexual orientation has nothing to do with choice. Our findings suggest there may be genes at play – we found evidence for two sets that affect whether a man is gay or straight.
“But it is not completely determinative; there are certainly other environmental factors involved. “The study shows that there are genes involved in male sexual orientation.
The nonsense part being that whether or not there is a genetic component it is still false to state that there is no choice in orientation.
We know this from simple observation of human beings. As an example, male on male sexual expression increases in all male societies, decreases when the same people are put into mixed sex societies.
There is therefore a matter of choice in it all.
That there’s a genetic and or developmental (say, exposure to hormones in the womb) component as well wouldn’t surprise me in the slightest. Indeed, I think they’re likely (for all my opinion matters). But “no choice” simply isn’t true as the behaviour of humans shows us.