I don't understand what happened to this thread. Last time I was here it seemed somewhat normal, but it escalated into a huge discussion about identity. It seems people can't deal with characters who are gender nonconforming. But the manga is pretty clear in saying that Kanda is a girl and her brother is male, no matter how they look.
Anyway, the last chapter was cute, but as an ending it was pretty underwhelming. Hoping for a sequel of some kind.
Therefore, homosexuality has almost nothing to do whatsoever with biological sex
I disagree. But then again, it would depend on your definition. If homosexuality had little to do with biological sex, homophobia would not be that big of a thing. The reason homophobia exists is because conservative societies cannot fathom the idea of people being attracted only to the same sex (i.e., society's definition of homosexuality). You cannot "see" someone's gender identity as it's psychological but you can usually recognize their sex. It's sex-signaling. Your brain identifies these sex characteristics and you can't help but be attracted to the same (or opposite) sex, or at least to people who appear to have characteristics of the same (or opposite) sex (like trans people who transition). It's just a visual thing that's innate. Similarly, for heterosexuality; it has a lot to do with sex given how it also involves sexual reproduction.
I just wanted to say that I agree with you. I'm a lesbian and I care about biological sex. I understand that not everyone is the same, but homosexuality is based on the same (homo) sex (sexuality). I didn't think it was controversial to say, especially in spaces that are supposed to be LGBT-friendly. If homosexuality wasn't biological, then nobody would be gay, since homophobia is a thing in most countries and logically you'd want to avoid being oppressed. But since you can't help who you're attracted to, it's not like you can choose.