There's a huge problem with sentencing discrepancies in the USA in general. Black defendants get sentenced to more prison time than white defendants for the same crimes on average: http://www.wsj.com/articles/SB10001424127887324432004578304463789858002

Then there's the problem of death penalty sentences; even in the states that do sentence people to death, there's no real consistency as to which murders are punishable by death and which ones aren't. We also shouldn't ignore the fact that 153 people have been released from death row since 1973 once their innocence was proven. Yes, 153 people were sentenced to death erroneously. So it's not hard to imagine that an innocent person has been put to death here in the "land of the free." The Todd Willingham case in Texas is a fascinating read on that topic.

I personally feel that we should drastically reduce our sentences for non-violent crimes (especially drug crimes) but I don't think we should lower our sentences for certain violent crimes. If you're convicted of a violent rape or murder then you should never have the opportunity to re-enter society like you would be able to in lots of first world European countries. It's probably impossible to create a perfect system because the USA does have a much higher rate of violent crime than other first world countries, but I think our prison system should attempt to rehabilitate most of our prisoners and completely separate the prisoners who have committed "minor" felonies from those who have committed psychopathic violent crimes.

TL;DR: Male pedophiles getting lower sentences than female pedophiles probably isn't the most pressing issue in America's justice system...