Before you read further, understand that I do not believe that homosexuality is genetic. Rather, I believe it to be a developmental issue. Whether it’s purely psychological or physiological, I cannot say. However, bad science bothers me, so this needs to be said.
To say that homosexuality cannot be genetic because it would die out with no direct transmission is faulty logic, that belies any understanding of recessive vs dominant genes.
Example: Using your logic of reproduction, there would be no muscular dystrophy of the Duchenne variety, as the afflicted rarely live to an age to directly pass on the disease. It would just die out with the afflicted. However the disease is genetic, it persists and it’s unlikely to go away. The reason is simple, unaffected females regularly pass the gene on from generation to generation.
No, I am not arguing that there is or isn’t a gay gene. That is irrelevant to me. If a gay gene does exist, that does not make homosexuality normal or a desirable trait or acceptable behavior in human moral terms or in evolution only terms.