If only there was a study which explained this... or maybe an "internet search engine" where you could find references.

I'll summarize for the lazy: taking everything else into account, men get 63% longer sentences for the same crime than women do.

If you look at crimes: http://law.jrank.org/pages/1250/Gender-Crime-Differences-bet...

About 80% are committed by men.

But 93% of inmates are men: https://www.bop.gov/about/statistics/statistics_inmate_gende...

There are any number of explanations for this. The most honest and rational explanations don't involve making men "bad" and women "good".