Is Asahi just babysitting her friends' children? That's what I thought at first, but the commentary mentions her "giving birth a lot". Did she get Mihari's drug? Or did everyone else? Do they have some sort of multi-relationship? Who's Asahi Jr.'s father? Is it her onii-chan? The author teases that last one a lot in Pixiv replies.
IVF and medical surrogacy are mature technologies that have been in use for decades. There are people conceived and born by these methods who are probably older than you. Also, adoption is a thing.
The idea that heterosexuals are the only people having children is ridiculous on its face and easily debunked—there are hundreds of thousands of families serving as counterexamples—yet I've been seeing homophobic idiots trotting out the same argument since before same-sex marriage was legalized. It's just as laughable a claim now as it was then.
>He thinks declining birth rates are a result of nonheterosexuals being accepted instead of the demographic transition following the industrialization of the world.