"It is?" said Mikey. "I don't understand, why do we call them that anyway?"
"What?" replied Jen. "I don't understand."
"Why do we call some people girls when they're young and boys when they're old?"
"Because they change from boys to girls or the other way, of course!"
"But... why do we call it a change?
"Because you change from..."
"No, I mean why do we use different words and switch them? If someone is born a girl and they get older and they grow a beard they're called a boy. Why don't we use the same word for 'someone who grows a beard' and 'someone who will grow a beard when they get older'?"
"What?" But Jen was beginning to see what Mikey meant. Jen remembered the original versions of the sexes. So if someone with a penis grows up to be someone with a vagina and breasts, she'd think of it as a boy changing into a girl. But if in this new world someone with a penis grows up to be someone with a vagina and breasts, as far as they're concerned everyone with a penis grows up that way. To them it would be one kind of person who is suddenly called different names, not one kind of person who changes into another kind of person.
"Why don't we just say man and woman? Everyone knows a girl grows up to be a man and a boy grows up to be a woman."
"Well, what do you think, Mikey?"
"I think it's parents who made it all up. They don't like to call someone a man or a woman when they're in school. Some parents will say 'young man' and 'young woman' but the rest still want to say boy and girl. But they messed up and they picked the opposite words."
"Now, that's not right, Mikey. When a boy grows up and becomes a girl and a girl grows up and becomes a boy we have reasons for using the words like that. For instance, girls can wear skirts. When girls grow up into boys they stop wearing skirts and when boys grow up into girls, they start. So you have a reason to use the same word for different people."
"What do you mean, Jen? I have lotsa skirts."
"But you just said that I started dressing as a girl."
"Of course. You have bras. Pantyhose. Heels. No kid ever wears those before growing up."
Which made sense, in a way. It was illogical for young people to wear something and then for older people to only wear it if they're of the opposite sex. After all, children like to imitate grownups. Someone who's going to grow up into a woman would anticipate growing up into one. If boys now grew up into women, anything that a woman did would be something that a boy also wanted to do before puberty. So women's clothes would either have kid versions that are worn by boys, or would not be worn by kids at all. Even playing with dolls--girls do it because they want to take care of children when they grow up, more than boys do. If boys grew up into women and women still took care of children more, boys would play with dolls, and girls would get the action figures.
Besides, before puberty, boys and girls look pretty much the same, except for genitals. In this world, young boys who wear skirts, play with dolls, swoon over male celebrities and so on would be exactly like the old world version of girls except for their genitals and maybe a name change.
"Look, Mikey," said Jen. "You don't have to worry. But I'm busy. Ask me some other time, okay?"
"Okay..."
Jen encouraged Mikey to leave and closed the door. This wasn't quite going as expected. She checked around for some old photos in files on her computer. One of them showed her at 8 years old. Yup, it was Jon, at his birthday, wearing a pink dress and happily holding a new doll. The banner in the background still said 'Happy Birthday Jon'.