When we're talking about the sexual abuse of a competent minor (ie an older teen) you're likely to find a higher proportion of male sex offenders, because overcoming the resistance of the child can be done physically. You get the odd female teacher who starts a relationship with a twelve year old, but it's statistically rarer.
When we're talking about complex families with long histories, drugs, alcohol and younger children, inter-sibling sexual abuse, and power-based sexual gratifcation without penetration - then I think the figures would be more complicated than you think. Society doesn't really think about these things, because they go on in the privacy of other people's homes - but female sex offenders do exist and the picture is more complicated than most people realise.
