There is a nice norwegian documentary about, that we are kind of brainwashed that genders are equal, and that the reason for underrepresentation is nurture, but in the movie they hint at different studies, that it is not solely nurture, these is really a lot in our genes too.

https://www.youtube.com/watch?v=E577jhf25t4 (it has english subs)

Or just check this part https://www.youtube.com/watch?v=E577jhf25t4&feature=youtu.be... if you don't want to watch the whole ~40min documentary