Am I just being a helicopter parent?

If you had a 3 year old nephew who regularly threw tantrums to the point he VIOLENTLY scratches his face until he bleeds or bangs his head on the ground over and over. Would you let your august baby around him? My son is starting to pick up on some of his habits like yelling “MINE!!!!” And “NO!” and I feel like its only a matter of time

My inlaws think we’re ridiculous and its a normal kid thing. My son is 19 months. He isn’t in in any kind of daycare so the way that he learns is by watching other kids and people that he’s around