Here are a few more questions to consider:

1) Do you remember this fear or repulsion beginning at a certain time in your life, or after a particular experience, sexual or otherwise?

2) Did you grow up in a strict environment where you were told that sex was dirty or bad?

3) Did you maybe witness something that caused this repulsion?

4) Was there any abuse in your past?

5) Is there anything else, outside of sex, that you feel repulsion towards or that you think is disgusting or contaminated?

I'm just trying to connect the dots here.