We live in a hypocritical morally confused society.  Its perfectly OK for our kids to watch Freddie Krugar mutulate someone....but not OK for our kids to watch a movie about a natural human function engaged by every living human being at some point.  Is the fear of ones daughter entering the business due to the sex or the danger?  I think a parent worries about a daughter being in danger first ... and the profession can be dangerous from several aspects including jail.  As to the sex..... a parent might worry the daughter is being desensitized to relationships..... or the parent is simply anal, uptight, confused....  jealous...... and probably morally hypocritical.