This is basically what I couldn't put into the K+ rating of SWDWHAFOOTA, namely… that. It's all scientific, don't freak out… (Yes, So Why Do We Have A Firebender On Our Team Again. SWDWWHAFOOTA). I just hope that it's within the rating… It is science and theory, isn't it?
Latvia's POV, takes place before they meet Jet but after England joins.
Of course, we forgot all about this
The night England joined our group, Sealand was oddly quiet. When we all went to sleep, I kept an eye out for him, and stayed up through Sokka's snores. As I predicted, Sealand ended up shaking England awake. England looked irritated, but he stayed quiet long enough for them to sneak off into the underbrush. I followed them, just in case.
Sealand dragged England all the way to a clearing far off from our campsite, and sat down on a rock. "What have you called me out here for, Sealand?" England asked, annoyed at his loss of sleep.
"I wanted to ask you something," Sealand replied levelly.
"Then why couldn't you wait until morning?" England snapped.
"I couldn't risk getting caught by the others," he said. Hopefully, by 'others' he meant Aang and the others, not me.
"Ask away then, and do be quick," said England with a sigh.
"I wanted to ask about your gender change," said Sealand. England fell over anime-style. "I read that girls tend to think differently than boys, and there were a bunch of other differences, too. Do you feel them?"
England was seething. "That… that's why you woke me up in the middle of the night for!?"
"Hey, it was important!" Sealand retorted.
They bickered and bickered until England sighed. "That's enough," he said. "I suppose it's time for you to learn this. Er… do you know how babies are born?"
Sealand nodded. "The stork brings-"
"Not that," said England, and then said, "Y and X chromosomes? Asexual versus Sexual?" Sealand shook his head. "No? Then…" He then began an explanation of sexual reproduction and the purpose of gender. Unlike his usual Sex ed, he seemed to be holding back a lot.  "…and that is how two gametes from each parent combine their 23 chromosomes and become zygotes, ensuring that the species has variation and diversity; therefore allowing evolution and natural selection to take its course," he finished.
"But how does the sperm get into-"
"That's all I can tell you on-screen!" England snapped. "Now, this is what I really have to tell you. Nations, unlike humans, have a different system. We can't reproduce, period. We're Anthropomorphic Personifications. Most nations are born out of the land and civilization- well, you were born out of my factory… which would make me technically you father instead of your brother…"
"Let's skip that part," said Sealand with a disgusted face.
"But here's what's important," England lectured on. "Due to many factors, even though we cannot reproduce, we still have gender and puberty and all that; since we're based off of humans. We all have these traits, but there are three attributes that humans have but we don't. One, female nations cannot bear a child. No matter what, they cannot conceive. Two, male nations can never get a woman pregnant, nation or human. However, that is only infertility; it does not mean impot-… moving on, it just that means that we just can't have children."
"So no demi-nations running around?" Sealand asked.
"No, no demi-nations," England agreed. "Last one: Female nations, due to the fact that they can't get pregnant in the first place… That time never comes."
"What time?" Sealand asked. "The only thing you did to explain it was say some boring sciency stuff."
"Ask someone else," said England, blushing. "Hint: It comes once a month."
Well, that couldn't have been more obvious for me. But then again, I lived for a long time among my citizens, and like all nations and micronations, I could read the minds of my citizens. Not that many think of stuff like that, it's just that I can see everything that all of my citizens ever experienced or thought, all at once. It's not overwhelming when you're used to it. I was really the only nation who had that kind of mind-reader.
But Sealand still had no idea. He kept on pestering England until England finally got fed up and said, "It's not all that bad, being a woman. I don't think any differently than I am as a man, and I'm still the same height. Is that all you wanted to hear?"
"No, what is that ti-"
"When you're older," he said. "When you're old enough to get past the science."
"Fine. I'll ask France, then," said Sealand in an effort to bait him.
"Don't you dare go near that bloody frog!" England snapped. He regained his calm, and added, "And if you do ask, you'll regret it. He'll talk you into you-know-what."
"I'll ask Latvia, then," said Sealand.
"Then ask him. He can't answer on screen, the author won't let you."
I snuck back, seeing that there was nothing else to hear. Besides, I had to pretend to sleep long enough for Sealand to wake me up again.
Sure enough, he did shake me as soon as he and England got back. "Psst! I need to ask you something!"
TO POSSIBLY BE CONTINUED!
 In one strip, France taunts England by saying how Sex ed in England (or the U.K., or whatever) is so shameful.
Yes, Latvia in my fics has more or less total mind reading powers on his citizens. This doesn't make a difference in this fic, since no one's Latvian, but in another one it might…