Because those preferences are mostly the result of sexism.
In 1970, there was no law against women being doctors or lawyers in 1970, yet less than 15% of graduates in those professions were women. Many people said the exact same thing you're saying now: oh, these are just natural preferences and aptitudes. Yet today, women make up 50% of graduates in those professions? Did something change in their genetics? Or did those professions just become less sexist?
What the heck explains 50% of accounting graduates being women, but less than 20% of CS graduates? Some weirdly specific gene?