Is sexual preference a result of biology, environment, or personal choice? Like many things (unfortunately), scientists pursuing this question are steadily moving in one direction, while those with an ideological agenda simply ignore the science and make up the answer they want.

We are a long way from understanding everything about human sexuality, but knowledge is not black or white. We have identified a number of factors that strongly suggest sexual preference is a biological phenomenon – something you are born with. There is no evidence to suggest it is a result of upbringing, and the idea that it is a choice defies not only the scientific evidence, but the experience of most humans on the planet.

Now a new study adds to the mounting evidence that sexual preference is just another feature of hardwiring and neurochemistry. In this series of studies scientists either blocked the receptors for or the production of serotonin in mice brains. They then observed their sexual behavior.

Unaltered males displayed a clear preference for engaging in mating behavior with females. But males that were blocked for serotonin displayed no preference. Further, when another male was introduced into their cage they would give a mating call and mount the other male much more rapidly and often than unaltered males.

Researchers could then revert their behavior back to that of an unaltered male by injecting serotonin into their brains.

Of course, this one series of studies in not the final word on the question of sexuality. It is but one piece to the puzzle. We also have to extrapolate from mice to humans with caution, but mammalian sexual behavior likely has some common evolutionary roots. This now gives us something to look for in humans, although of course we cannot reproduce this kind of experiment on people.

While there is no single gene for sexual preference, and sexual preference itself is not a simple dichotomy, it is increasingly clear that sexual preference is largely determined by the biology of our brains, not anything that can be considered choice.

The neuroscience question at this time is, how much of sexual preference is genetic vs epigenetic. Is it mostly in our genes, or is it in the hormonal environment of the womb. Of course, it is the genes that largely determines that environment, but genes are not the only factor, opening the door for epigenetic factors to trump genes for gender.

Perhaps when we understand enough about the neurobiology of sexual preference, it will ironically become a choice – something that we can change about ourselves if we choose. Think of the implications of that.