How to explain that in a way that didn't make him sound insane? Going into the whole story would involve a lot of explanation, a belief in magic, and probably a lot of alcohol on Magneto's part, but Billy settled for the simplest one.

"Yes and no. I mean, I was kind of adopted, but I was never alone. I have amazing parents. It's only been about a year or two since I knew about "

It helped that it was true.