Always amazing how nature floods the brains of parents with the right chemicals to actually deal with raising a child.
I'm childless, yet have experienced glimpses of this when holding a little one. I've been puked on too, but it was strangely not a thing. Now if an adult puked on me, I'd end up in the shower like the guy in The Crying Game.
Also tried to change a nappy. Nope. Gonna need way more oxytocin and whatever hormones nature delegates to the parents.
Oddly enough I am alright with nappies. Except when I am peed on but I suspect that deep down few of us are happy with being peed on lol :0)