Being gay isn't a choice. If it was, no one would choose it due to the way that so many nazi pinheads (you might call them religious freaks) act. And if anyone thinks that it's is a choice (naysayers pay attention), then that means anyone can choose to be gay, right? Well, if that's the case, then that means anyone can choose to be straight as well. That's only logical. So, why did you choose to be straight? Think about that for a while. You never chose because it's basically (in simplest terms) programmed into your brain. And if it is a choice, then you be gay. Sit down for five minutes and try to make yourself attracted to the same gender. Go ahead and try it. I guarentee you, it won't happen. You can't choose to be gay. It's just not possible to choose that.
There was a study done on the chemical balances in the brains of 90 individuals. Some were homosexual, some were heterosexual, some were bisexual. It was determined that the chemical balance in a gay males brain were very similar to a straight females brain. Same goes for a lesbians to a straight males. Depending on which gender the bisexual preferred more, determined what his brain's chemicals were more simlar to. I'll explain that part of it later.
These chemicals balances are most likely caused by genes. Now most people say, "Well there's no gay gene, so that's not possible." According to science, it is a not a choice. Scientists discovered that women tend to have more children when they inherit the same genetic factors which is linked to homosexuality in men. This fertility boost more than compensates for the lack of offspring fathered by gay men, and continues the “gay” genetic factors in circulation. Gay men have three clustered chromosomes: 7, 8, and 10, which determine the sexual orientation. Being homosexual is inherited in the genes, and is neither a disease nor a sickness.
"Genetic investigations provide strong evidence for a heritable component to male and female sexual orientation," Rahman Q et. al.; School of Psychology, University of East London
"The survival of a human predisposition for homosexuality can be explained by sexual orientation being a polygenetic trait that is influenced by a number of genes," Miller EM.; University of New Orleans.
We only know of 5% of what the human genome does. 95% of the human genome is labeled as Junk DNA (
http://en.wikipedia.org/wiki/Junk_DNA ). It's also believed that this Junk DNA has an impact on sexual orientation, as well as other things.
When someone is maturing through their teenage years, chemicals in their brain get distorted and for a period of time they find the same sex attractive.