Stubbornly gender-neutral way to address or refer to your older sibling? (Wait a minute...what about non-binary?)

Question

I believe Mandarin, Cantonese, Tagalog/Filipino/Philippine and English (I'm a monolinguist from HK and the Philippines) don't have this, and so Japanese probably doesn't either, but here goes:

1. Is there a gender-neutral way to refer to your elder/older sibling like if someone were so stubbornly gender-neutral and wanted to say

My onii-chan/onee-san wants me to go home early.

How would this be said? Maybe

My toshiue no kyōdai wants me to go home early.

?

Forget how strange this sounds. I'm sure it sounds very strange in Japanese as it does in the aforementioned languages, but that's the point. The person is being very stubbornly gender-neutral. The point is to be stubbornly technically correct, however strange.

But wait...maybe it shouldn't be so strange. After all, how would you refer to 2 older siblings of opposite sex? I'm guessing toshiue no kyōdai tachi...?

2. Is there a gender-neutral way to address your older sibling?

In English people can say 'big sib', the way the way 'big bro/sis', but I'm sure 99% of English speaking people don't do this. Still, technically I guess this is 1 (highly impractical) difference between English and the other aforementioned languages. I don't know of any 'big sib' version for Mandarin's jie jie/ge ge or Tagalog's ate/kuya.

If Japanese ever did have such a term, then I can imagine 99% of Japanese speaking people don't do this, but humour me, how would a stubbornly gender-neutral person address their older siblings (or perhaps the older sibling if the stubbornly gender-neutral person who wants to be addressed gender neutrally) ?

Onii-chan/Onee-san, why do I have to go home early?

How would this be said? Maybe

Toshiue no kyōdai-chan/san, why do I have to go home early?

Again, forget how strange this sounds. The point is to be stubbornly technically correct, however strange.

Note: Wait I just realised...

There should totally be a thing like this...how would we address older siblings who identify as non-binary (or whatever Asia Kate Dillon's thing is) ? (And then if this is resolved then let's go back to the stubborn thing)

Answer 1

First of all, nearly all Japanese sentences are naturally gender-agnostic, so you never have to be "stubbornly gender-neutral" when speaking Japanese. In English, it is very challenging to talk about a certain person for a long time without using either "he/his/him" or "she/her" at all. You have to be "stubbornly gender-neutral" to do so. In Japanese, however, we don't indicate someone's gender unless it's necessary. Our way of speaking does not have to change at all depending on whether the person being discussed is male, female or nonbinary. All those issues we recently see around English personal pronouns do not occur in Japanese. For instance, compare this "stubbornly gender-neutral" English article and this perfectly natural Japanese article about the same manga artist.

1. Is there a gender-neutral way to refer to your elder/older sibling like if someone were so stubbornly gender-neutral and wanted to say

When you want to ask "Do you have any siblings?" in Japanese, you can just say 兄弟はいますか. No one would think you are specifically asking about male siblings. If you want to ask only about elder siblings for some reason, 年上の兄弟はいますか or 上の兄弟はいますか is perfectly natural (though お兄さんかお姉さんはいますか is equally fine). See: When is 兄弟 interpreted as "siblings" and when is it interpreted as "brothers"?

You seem to be aware of this, but 兄弟 is a word that means both "sibling" and "brother". 姉妹 specifically refers to sisters (it's used only when gender is emphasized). Visually, it's like this:

  兄弟
  ／＼
兄弟 姉妹

You can find similar patterns in god/goddess, actor/actress, 王/女王, etc. See: If 'little girl' is 「少女」, then why is 'little boy' 「少年」?

It's true that 兄弟 is made of 兄 and 弟, so it does not appear to be very gender-neutral. People who worry about this sometimes write this word intentionally in all-hiragana when used gender-neutrally (年上のきょうだいはいますか), but this is not a hard rule. The last resort is 兄弟姉妹 ("brothers and sisters"), but you rarely need this in speech.

2. Is there a gender-neutral way to address your older sibling?

No. 兄弟さん is extremely strange. Simply, you can use their real name or nickname, or stick to ねえ/なあ/etc ("hey/yo"). The same for parents; there are words for "Dad" and words for "Mom", but there is no word that can be used to address both of them. Some people address their parents by name, as if they were talking to a friend, so that would be an alternative.