Boys are dirty. Dirt in the snot running from their nose dirty. Spit in food-spit in your food dirty.
Boy are painful. Kick you in the nuts and laugh painful. Ignore you painful, ignore you and laugh about it painful.
Boys are careless. Break shit careless, break expensive shit careless, break your expensive shit careless. Break their expensive shit that you bought careless.
Boys take up space. You gotta buy a big car if you have two of them. They crowd you out of chairs, couches, dinner tables and some relationships. Sometimes when they're close they smell (see "boys are dirty").
Boys are loud. Boys yell so you'll hear them. Boys yell to be heard over other boys. Sometimes boys are loud just because they want to be.
Boys don't sit still. Boys wriggle, move and fidget (see boys break things). Boys aren't good at quiet time and only like nap mats when they pretend to take a nap.
Boys are genuine-wide eyed, grateful to be taken for the ride, heart broken if ignored genuine.
So, who should know this. The people who work with, interact with raise and have a passing engagement with boys should know these things. But that's not half as important as having boys know this. Boys can get caught up in being a 'good boy' trying to please mom, dad, teacher, coach. While I'm all for this kind of motivation if the people who are here to raise boys lose sight of who they're raising things can get messy.
So, if you're raising, coaching, interacting with or teaching boys--know who you're dealing with.