OK I don't know if goat kids do this too cause I've never raised any, but lambs from the day they're born have to punch their mama's udder in order to get milk out, that's how lactation works in ewes, so the instinct is very firmly ingrained in their little baby lamb heads to "punch the dangly thing on adult's belly in order to dispense food." By the time they're big enough to wean, they will sometimes punch hard enough to lift their mama's back legs off the ground in their enthusiasm for food.
I'm sure you see where I'm going with this. One year I had to pull a few of the ram lambs two weeks early for reasons (nobody @ me they were fine) and because they were smaller than usual and there were only a few of them I didn't want to dump them straight into the pen with all the big guys to get beat up. Instead I put them in a smaller pasture and tossed the Boss Ram in with them as a babysitter because he's always been relatively gentle with lambs and letting The Boss get used to new guys alone usually helps with dominance fighting later.
So here is this big, dominant ram, undisputed king of his domain, locked in a pen with four of his newly weaned mini-mes who have never shared a pen with an adult male before. He's got the biggest horns and the hardest head on the farm, he's ready for anything.
Except. The lambs have no interest in bashing skulls. The lambs are hungry. The lambs see an adult with dangly bits in approximately the same place as their mama's dangly bits. Their entire three months of lived experience tells them punching those dangly bits results in food.
That ram, who had never before run from a fight, spent a very uncomfortable and confusing time being chased around the pen by four miniature copies of himself, all of them crying at the top of their lungs and very determined to punch him in the nuts.
