Sure. But human experience show us whether or not such standards work.
NAMBLA claims that man/boy sex doesn't hurt anyone. Who's to say that their opinion is wrong?
We have the ability to do statistical studies on the effects of sexual intercourse between adults and children. No one without an ulterior motive (such as NAMBLA) can seriously claim that 5 year-olds aren't harmed by sex with an adult (both physically and psychologically).
They have statistical studies to prove that the children of divorce are happy, or that abortion doesn't hurt anybody, but it doesn't make it so.
Sometimes you have to get your head above numbers, and understand that there is a source for morality beyond ourselves.