My DS is 17. Hi has never noticed that him and Dad were different. When he was about 8ish (can't remember the sure age) he did ask me why his penis was in the inside and friends was on the outside. I told him that some parents feel like it is best to remove the skin that covers the penis when their boys are born but we thought it was best to leave it alone. He made a face something like this
and said you mean that they cut off part of friends name penis I said yes and he seemed to think that was a very bad idea to say the least.
As he has gotten older I have asked if anyone has ever said anything to him and he assured me that anyone talking about and admitting that they noticed someone else penis would be the one made fun of not the owner of the penis.
He dates, he plays sports, has been caught skinny dipping
and does pretty a normal teenage boy stuff with out being ostracized by his peers. He has also never, never expressed a desire to have his foreskin removed