I have 3 boys - 16, 9 and 17mons. Do they ever stop?
My lil guy gets mad when I put the diaper on, 'cuz he can't get it anymore!
Actually, his circumcision isn't the greatest (GGRRRRR to the doc that did it!) It often gets stuck in. My Dr said to "Let PooWee work it back out!" Yes, she encouraged him to "play" with it!
I think it's normal for boys and girls to be curious of that area. It always covered up unlike their toes and ears, which they play with too.