I hold no strong opinions towards homosexuality one way or the other; I'll personally refrain, but don't apply my personal tastes to the rest of the world.

I remember seeing some articles a while back, and in some online debates, that there's been evidence in favour of a genetic component of homosexuality. I ignored it back then (before it became legalised), since it didn't affect me. However, after deep thinking, I started to seriously doubt those stories.

My gripe is this, based on my extremely limited understanding of Evolutionary Biology, organisms with genes which boost survivability, will tend to become more abundant. Genes that made organisms more fertile and reproduce more, will tend to become more abundant.

So, if say a particular gene, reduced effective fertility of organisms, that gene may be expected to be absent after a while. Fewer organisms with that gene would reproduce each successive new filial generation. There will be a diminishing marginal increase in the population of these gene bearers, before there eventually starts to become negative growth. I expect that population, may eventually find themselves in extinction, or on the brink of it.

In the few 100,000 years that Homo Sapiens have walked this planet, I guess there's been sufficient time for a population of genetically predisposed homosexuals to become extinct, or reach its brink. Certainly not the 5% - 10% estimated population we have today.

As such, I am unable to understand how homosexuality might be determined by genes in spite of natural selection.

My understanding of Evolutionary Biology may be severely lacking; especially as my teachers in the subject believed it was blatantly false, and were not really interested in making their students understand it. Some even going to the extent of making it seem as ridiculous as possible (I live in a country, where more than 90% of the population are genuinely religous (as in they truly believe in the existence of God) in one form or the other). I would appreciate answers to my question.

Of course, whether or not treatment of homosexuals should change, is another separate matter. It certainly does not follow from any conclusion of this inquiry; the answer to this question, is irrelevant as far as LGBT rights are concerned.

  • 1
    $\begingroup$ Note that there is no question in the boy of the pot. Only in the title. That makes the post arguably slightly unclear. The title would let one thing you are interested in the mechanistic mechanism by which genes can affect sexual orientation while the body of the post clearly talk about selection pressure toward those potential genes. $\endgroup$
    – Remi.b
    Mar 23, 2017 at 15:03
  • 1
    $\begingroup$ I guess my question would be: How can homosexuality be genetic despite natural selection? $\endgroup$ Mar 23, 2017 at 15:55
  • 1
    $\begingroup$ Is this any different from How can homosexuality evolve despite natural selection?? Can you please try to clarify in what way these two questions are different? $\endgroup$
    – Remi.b
    Mar 23, 2017 at 16:19
  • 2
    $\begingroup$ Take the advice of @Remi.b, check out the Berkeley site. It's a mistake to assume evolution can eliminate all traits that do not appear to offer a selective advantage. $\endgroup$
    – bpedit
    Mar 23, 2017 at 19:08
  • 1
    $\begingroup$ Consider that evolution works by populations, not just by individuals. A human tribe that has a proportion of its people not attached to their own offspring seems likely to be stronger than one made up of competing male-female pairs. To take this to an extreme, you might ask how eusocial creatures like ants, bees, and naked mole rats can be successful. $\endgroup$
    – jamesqf
    Mar 23, 2017 at 19:37