Some hard numbers would help this discussion.
Is this a 3 sigma deviation? Maybe. Or could it be that, on average, women might be drawn to educational software more than other types? Doesn't sound unreasonable.
Regardless, your insistence on an explanation shows that you're still stuck in the bad old days.
In the same vein it is interesting to ask why most companies receive more male applications. Without asking these questions, how can there ever be an improvement (except for random luck)?
Internships tend to be a bit less one-sided, but the skew is still quite high.
This sucks. I want to receive those resumes, for what I hope are obvious reasons, but I don't ever receive them.
Given that, I can't help but wonder whether:
1) You have a completely different applicant pool
or
2) You somehow changed your application process in a way that resulted in a 2:1 female:male ratio.
I don't think those are terrible questions to have. The answers could be enlightening.