There are allegations that Trump doesn’t want to release his tax returns for fear people will find out he donated to NAMBLA
http://nymag.com/intelligencer/2016/08/many-people-are-saying-donald-trump-donated-to-nambla.html
I’m not saying he did donate millions of dollars to NAMBLA. I’m just saying I’ve heard people say he donated millions to NAMBLA. That would make sense why he doesn’t want to release his returns.