No the propensity toward violence is not a birth defect.
Didn't say it was, I asaid it COULD be viewed as such from a moral high ground.
Chimpanzees are violent, territorial, and abusive to their females.
They don't know any better.
That we are closely related to them means very little in reality.
I am far more closely related to Osain Bolt than to any chimp but the chances of me breaking the 9 second mark in the 100 meters is ZERO.
If homosexuality has it's origin in genetics, then heterosexual parents everywhere are passing those genes on to their offspring. It would not be a birth defect but a genetic trait. Just because it is not subject to natural selection does not mean it will die out.
There are many genetic defects that are passed on from parent to child, doesn't change them being defects.
I think maybe you are having issues with the term " birth defect" and that's fine, I don't care much for it either, would you prefer " unproductive genetic trait"?
In terms of propegating the species ( what sex is used for at the genetic level), homosexuality is NOT a favorable genetic trait and nothing can change that or change that some will view it that way.