 [ Symptoms ] when do boys start to have sensitivty in there privates son is 3 and shows no sign or reaction if he got hit he is in underwear his sister hit him by accident in his private and he had no reaction his dad has asked him if he hurt his peepee but he just says no and that was when he was on his bike and slipped on to the middle bar on the bike should i be worried that he has no sensitivity there or is that normal [ Disease ] that could be very possible i suggest getting blood work done talk to your family doctor it is possible she will refer you to a specialist my biggest advice is to be open and honest with your doctors