I never tried to kill any kids, goblin or otherwise, and I played both sides of that coin. The tiefling kids we all dead at goblin hands when I found them. The goblin kids were never around once you start to wipe their camp and that goes for their bodies as well. But the druid cove was littered with their bodies and there were far more tiefling children than goblin. I felt bad for the mute tiefling kid though.
But I don't want either race's kids or any kids to be removed from the game. Baldur's Gate better have kids and I loved the lil scam the tiefling kids had going on.