Easy answer to the question...
Based on more than 8,000 autopsies of male and female
patients without brain diseases the normal brain weight
of adult males and females in relation to sex, age,
body-weight, and body-height as well as body mass
index were calculated.
The average brain weight of the adult male
was
1,336g, and for the adult female
1,198g.
[PubMed, PMID: 8072950]
This extra 138g explains why men dominate
the scientific, mathematical, medical, research
and engineering fields.
And culture—the female to get married, to have and look after the kids etc—has no role in this? What about a brain mass:body mass ratio?