Is all homophobia rooted with religious beliefs

[The Magic Pudding]

male homosexual orientation in mammals is caused by sexual antagonistic selection.

This article describes sexual antagonistic selection.  It is a reasonable explanation of biological influence.  There may be others.
I would expect cultural, including family influences to be important.
http://www.slate.com/id/2194232

What happens when the older more macho brother dies?

I didn't actualy say more macho.
There is a history of bad ass homosexual or androphiliac warriors.  
They may not pass on androphiliac genes directly, but the article above suggests their female relatives will be more likely to.

[Martin TK]

I actually went to, and I don't recommend this, to a Christian forum to ask about homosexuality.  I was really shocked by the outrage against homosexuality I got from those on the site.  One guy actually said he would go up to a homosexual and say, "You make me sick, I want to vomit all over you."  Of course that was the nice thing he said.

I asked a question that no one on the site could answer or would answer.  I asked where did this "hatred" of homosexuality came from, the Old Testament or New Testament.  Of course I was quoted several verses from the OT, that explained why they were against homosexuality, so I asked if it was ok for me to stone my kids for being disrespectful.  I thought if they are going to pull things out of the OT, then so could I.  Well, you can imagine the response, it was pretty funny actually.

[Thumpalumpacus]

ITT, Matrin confesses to trolling