Older brother

Daisy

Okay I have a 6 year old a 4 year old and a 1 year old all boys so I let the two older ones play in the bath alone while I clean and I look in to see my oldest grabbing my 4 year olds privates and laughing what should I do he has started coming home from school talking about weeners and I am concerned what he is hearing what do y'all think