Weapons of war in my pacifist household

We don't allow our children to have guns in the house.  You'd think that would mean we wouldn't have guns in the house.

But no.

Ari makes guns out of biting his cheddar cheese into certain patterns.

Xander goes to do art and rises from the table with his own hand-crafted gun; a straw, construction paper, and tape.

I'm one of the most "gender as a social construction," non-normative gender roles person I know.  But all that said... is it something in boys' nature???  None of my friends with girls seem to have this issue.