Today, my son had a serious meltdown. He (4 years old) was told by his sister (
that he couldn't carry a baby in his tummy. He argued with her very insistently. Then the argument was brought to me, and when I calmly assured him that he was not able to carry a baby in his tummy because God didn't make boys with the necessary organs to do so, he ran to his room threw himself into the closet and sobbed before I could tell him anything else. It was as if I had stolen his toy and ripped in half. It was that serious.
After I calmed him down, I was able to assure him that one day when he is an adult he might met a girl who would happily give him a child. He still wasn't comforted by this as he wants to be able to carry a baby around in his tummy. Try keeping a straight face through all this while your son is very serious about his intent on carrying a baby in his tummy. I was sure that I explained only mommies can carry babies in his tummy a while ago, but he apparently he didn't hear me very well.