Sit in any classroom or ask any teacher who their problem children are, and they're almost always boys. They're louder, more violent, more likely to disobey, and have a harder time sitting still.
Are all boys a problem? No, of course not. I imagine a lot has to do with home balance, the involvement of two parents, etc. Are all girls good? No, of course not. But statistically there is a difference. This is true until they settle down in their mid to late twenties...just look at insurance rates.
Maybe it's not biological and is cultural, but it's true from a very young age through young adult that boys are less able to sit still, be quiet, and listen. And school is structured in a way that punishes those traits, and we as a culture medicate boys to make them calm down.