Well, Smokin got me there.

A 13yo male would stick his dick almost anywhere and it could be troubling because of STDs and such.

Even so, male and female psychological development is different and should be taken in consideration in the argument, therefore I believe that the kid should pay 2 or 3 visits to an specialized psychiatrist, then he could say if the kid is apt to testify. If the case is that the kid wanted to do it and had an emocional background then she could get less jail time if any...
That should apply to girls as well, but I believe it would be very hard to any men getting away with it, because of difference in development.

Women here in Brazil menstruate as young as 8yo and the hormonal cycle changes everything. Because of that we only considerate rape when the kids are under age 14 (so If a guy sleeps with a 14yo he'll not be charged with rape, only seduction crime if someone like their parents make it, and it's not really punished).

When I was 13 I deffinitely would have sex with a hot teacher but I would also definitely use a condom, because I already did have sex ed and I believe I was already mature enough

That being said, I'm still 19yo and may have no idea of what real maturity is, even though I'm a second year medicine student and therefore my opinion mean just a bit more than nothing.