We have one gun in the house that a friend bought my 4 year old. I was always no gun, no gun but honestly my boys will pick up a matchbox car and pretend to shoot with that. I think they picked up the whole shooting thing from my 10 year old brother. I tell them we never, not even in play point guns at people, sometimes they listen to that, sometimes not.
Perhaps you could redirect him away from pointing it at people? Or perhaps get him a water pistol and see if he can knock objects off a post with water? Basically try and redirect his attention away from shooting people: I think kids will play with guns/act out playing guns but you can help direct the play.
Dd is three and would have no clue what a weapon is and I hope to keep it that way!
You know where my son learned about guns? Beatrix bloody Potter.
He doesn't actually have any toy guns, doesn't need them. He doesn't often play guns - he's more into constructive tools - but he does like to hunt and kill things somethings. no idea where it comes from.
Oh, and sometimes he steals my dad's invisible weapon from him to turn other things invisible...
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