[rfhjt]

And this is not impossible. The obvious example is the north vs south Korean. The same people, but different nutrition, different lifestyles. Now the NK people are obviously smaller and I'd bet, have a much lower IQ (the lack of food doesn't help with math activities!) I'm certain that there are many subtle differences in how people live in Netherlands and Denmark.

[cygx]

How do you expect this to work: To get a gender imblance, only one of the sexes would have to suffer these adverse effects due to, say, nutrition. That would likely still be caused by social factors...

[rfhjt]

Because makes and females have different nutrition, different habits and fir example use different drugs. It may be something silly like different contents of birth control pills. It's not a secret that small changes in amount of consumed zink, calcium or iodine make big impact on body and mental abilities.