It comes from not obeying God. Let's say that you have eating a certain type of food that we are not to eat.
So, I take it, you don't believe people are "born homosexual"?
But no, that God didn't made humans to have relations with the same sex. They will not be able to procreate that away. And homosexuality is not a normal functioning behavior for human beings. Incest is not a normal behavior as well. But a lot of people do practiced it for hundreds of years. But that doesn't make it to be categorized as a normal behavior..
But incestuous couples can procreate. So procreation is not the issue that makes homosexuality and incest comparable.
"Normal" of course is a concept fraught with danger. It was not 'normal' for women to wear pants until quite recently- and that is actually forbidden in the Old Testament.
But you don't see too many Christians saying it is a sin for women to wear pants.
Some people has gotten so use of looking at children of incest, that as if it is normal look. Incest affects the physical features and mental behaviors. Long ago, people knows how to detect those that are from those that had practiced incest. As God had told the people in those days, that if they were to follow these laws, that they will live a good long prosperous life. Without any health issues or defects of any kind.
Children of incest 'cult' found living deformed and mute in Australian valley | Daily Mail Online
Deuteronomy 5:33 Walk in obedience to all that the Lord your God has commanded you, so that you may live and prosper and prolong your days in the land that you will possess.
Matthew 23:27 “Woe to you, teachers of the law and Pharisees, you hypocrites! You are like whitewashed tombs, which look beautiful on the outside but on the inside are full of the bones of the dead and everything unclean.
John 9:2 His disciples asked him, “Rabbi, who sinned, this man or his parents, that he was born blind?”
Back then, the people were ignorant, that they did not know what to eat or what to feed their cattle or flock. But now we has scientist. instead of God to show us the way how to live a long and prosperous life....
It is linked to this disease..