Like a lot of contributors to this thread, my first answer to the question is "not with me". My childhood was loving and supportive. My mother spanked me exactly once - very clumsily and ineffectively, in blind anger - and it was her anger that hurt me then.

My difficulty in puberty was finding myself turned on by ideas of torture and slavery when I had been raised to believe that violence and oppression were the greatest evils.

I don't believe that there is a higher incidence of abusive childhoods among us, but I do suspect that because what we do has such power to release and relieve old hurts, BDSM people are more likely to have come to terms with past abuse and to be able to talk about it. So this may create a false impression that there are more abuse survivors here than in the vanilla world.

It's that well known effect where improved reporting creates the appearance of a greater problem.