I have an anecdotal evidence related to this. In the secondary grammar school, I participated in the so-called math olympics, which consisted of three levels, s

I have an anecdotal evidence related to this. In the secondary grammar school, I participated in the so-called math olympics, which consisted of three levels, school level, district level, and then country level. It was not related to "carrier choice", and both boys and girls participated in the school level . Once I managed to advance to the country level (the winners there go to the International olympics), and from around 100 participants, I hardly remember there was any girl... probably a few, but certainly less than 5%. And there wasn't any artificial discrimination, nobody cared if you are boy or girl.