system
A chat on subreddit /r/NoStupidQuestions
human
&gt; Most modern human behavior is nurture. 

&gt; Men's brains are not noticeably different from women's.

These are extremely bold statements that would require very rigorous evidence from many disciplines, from neurology and biology to psychology and anthropology. Where is it?

For example, men have 10-20x more testosterone than women. How did you quantify its effect when you concluded that nurture determines “most” modern behavior? In order to do that you would first need to determine the exact interrelation between testosterone and aggression, and we can’t even do that, it’s too complex. And that’s just one factor, you then need to offset that with all other (also quantified) biological, environmental and cultural factors affecting aggression, some of which we probably aren’t even aware of yet.

I seriously doubt you or anyone alive knows enough to make pronouncements like that. Too many unknowns.
gpt
What we do know is that newborn children, that are just a few days old, already exhibit gender stereotypes, even when they are intentionally kept in gender-neutral environments until the test is conducted. We also know this happens with monkeys too. This is very strong indication that not everything is sociologically explained.