Discovering they have different 'bits'

My DS is 17.5 months.

Something funny happened today. I was giving him a bath in the tub and he reached and touched me down there, felt around a bit and then did a gesture with his hand that we taught him meaning 'don't have or all gone or no more' i think he was saying i havent got what he's got!
i would have thought he's a bit young to realise this. He has seen his daddy in the nude and we have told him you have what daddy has, when he looked at DH curiously. We havent explained mum's bits. He goes to day care and would have seen girls having their nappies changed.

Is it common for toddler to realise they have different anatomies at this age?

TIA :D

A friends DS pointed and laughed at Nina (when they were in the bath) one time and asked 'what's that mummy'! He was 18 months at the time. It was actually quite funny the way he did it. As he is showing interest, tell him, and tell him the real words for all the areas. You don't need to go into detail about it at his age, but just say 'that's mummy's vagina' or something like that.

thanks jodi. i didnt tell him 'vagina' but did tell him, 'amma's different from you, I havent got what you have, amma's a girl'
next time will use the words :D

Aw cute! Can't believe our same EDD boys have grown so big!
DS is entirely uninterested in his own bits, let alone anyone else's!
Although he has a sudden obsession with 'boo'. Seeing as I am not bfing I am trying to discourage it and we talk about 'boo' books instead, but he is always trying to get his hands down my top when we cuddle and goes 'boo boo boo'. :rofl:

ash - thanks! haha. poopy has been playing with himself since he was 4 mths!! yes, it's amazing they have grown up so much!
im giving poopy first and last feeds and at night he puts his hand down my top, and lately he says more! more!

Jazz seems to be a little facinated when she see's DH go to the toilet and watches the wee go from him to the toilet but I don't think he's usually naked much when she's up, neither of us are actually. She sees us get dressed but that's it really. She does look at my boobs a lot and then touches her chest though and I just say "Mummy's boobs" when she looks at them