I'm a fan of the idea that orcs aren't GRUG SMASH chaotic retarded but instead fiercely territorial like some native American tribes, and that humans sometimes make territory pacts with them in order to establish trade routes and shiet, which also includes consensual/semi-consensual interbreeding to make sure either side doesn't just start violating the pact all willy-nilly. Which results in half-orcs raised in human settlements who behave more like humans, and those raised in orc settlements that behave more like orcs.