who knows is the correct answer. Many come from upstanding Christian families so I don't know.
There are many things that can cause a person to become attracted to the same sex; even being attracted but not acting on the attraction can weaken that attraction.
The important point is that the fact that there are tens of thousands of former homosexuals proves that it is not inborn, and certainly not immutable.
Even if some people have more of a tendency to be attracted to members of the same sex (which point is debatable at best), it is a fact that people, if they want, have a good chance of being healed from it.