I had an anonymous comment to a previous post on sex which asked:
So if sex can be explained by science as a preprogramed procreational act that we are all compelled to do, to further our species, please offer a scientific explanation for homosexuality.
So the example I thought I'd start with is Tweedledum and Tweedledee:
Tweedledum and Tweedledee Agreed to have a battle; For Tweedledum said Tweedledee Had spoiled his nice new rattle.
What if Tweedledum had been gay? What are the chances that Tweedledee would be gay too? Twin studies are fascinating for asking questions about the influence of genes on behaviour. Twins share DNA. Twins also often share the same environment. So by comparing monozygotic twins (twins who grew from a single egg) who grew up together, to those that didn't and by including the results of dizygotic twins (twins who come from two different eggs, but shared the womb) we can build up a picture of what influences somebody to be homosexual.
There is no consistent overall finding, but let's look at one study:
J. Michael Bailey and Richard Pillard also studied the gayness between MZ twins, DZ twins, and non-related adopted brothers. They examined how many of the sample population examined were gay and how many were straight. They found that 52% of MZ twins were both self-identified homosexuals, 22% of DZ twins were so, and only 5% of non-related adopted brothers were so.
So let's assume that this finding is generally representative. For males then, if your monozygotic twin is gay, you have approximately 50% chance of being gay yourself. If you are dizygotic twins, or adopted, that percentage quickly falls. So obviously there is a genetic component to human sexuality.
However because the concordance rate is not 100% it follows that being homosexual is not an inevitability, as much it is an interaction between a persons genetic makeup and the environment they find themselves in. As with any complex human behaviour, it is not simply that there is one gay gene, without which you will not become homosexual. Instead there are probably a range of different reasons why people choose to engage in homosexual behaviour. One reason may be biological. Others may be social.
Perhaps we should just view people's sexuality as their own business. If two consenting adults wish to have sex, I see no real reason to stop them (regardless of gender). Finally my advice to Tweedledee, if Tweedledum really were gay, would be to just join Second Life. A place where real world gender or biology really doesn't make much of a difference anyway!Go Top