It's certainly not a sin, but is it really "normal?"
Other kinds of birth defects occur, but we don't call them normal.
I am opposed to discriminating against homosexuals, but I'm also opposed to discriminating against handicapped people as well.
It is VERY clear what the bible says on this, and yes, it is called a sin.
Leviticus 18:22
You shall not lie with a male as with a woman; it is an abomination.
Leviticus 20:13
If a man lies with a male as with a woman, both of them have committed an abomination; they shall surely be put to death; their blood is upon them.
1 Corinthians 6:9
Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived: neither the sexually immoral, nor idolaters, nor adulterers, nor men who practice homosexuality,
There's many more if you need them.