what penis bit? the bit where you see the basic workings or the bit where intercourse is explained?
My ds1 was 6 when I was expecting ds3 he asked alot of questions and I gave him the answers-Ive explained everything, I dont want him to be embarrased by his body or what it does and as consequence now at nearly 9 he talks to me about anything has no hangup about being naked around me or visa versa.
The knowledge he has about sex and reproduction was given to him in an age appropriate way but truthfully, he can now distinguish between the playground chatter and doesnt feel "a bit lost" with regard to this grown up stuff which is naturally talked about by kids as it is shoved in their faces everywhere from music videos to tv adverts, bilboards and so on.
Children see sex everywhere it is used to sell everything! it must be quite odd for kids to see this adult world played out for their eyes in such a way! by arming my son with the facts and the opportunity to come and talk to me about anything at anytime i feel I am doing the absolute best for him.
And yes of course a child can know about her clitoris! why on earth not!! and with regard to sex for pleasure, yup that too and you know what even rape-it is in the papers, radio and tv news my ds can read and has asked me these questions, affairs, brothels etc etc i remember asking my mum at 12 what virginity was (after watching grease!) and she told me she would tell me when I was older, she never did! but i worked it out from the playground, I dont want that for my children, I do believe that open and honest explanations about things are the way forward, Im not telling him to go out and have sex! I am explaining the emotional things as well (age appropriate)
I came from such a prudish household and am determined that when my sons need to talk to me about this stuff they will already know they can! they will already feel comfortable with it as a subject because they always will have been.
Its just sex you know!