My children and I investigate their interests that I don't support. We go to the library and search out books on the subject, or find knowledgeable people and get firsthand information that could possibly help bring us some unity on the idea. Use it all to reinforce learning and it makes it more fun because the child is already interested in the subject. It all seems like reverse psychology, but it is good that you look a fear squarely in the face. Get all the information about it and it suddenly doesn't seem like such a monster.
Children learn more from our life than our words.