References to brothers or sisters, or mothers or fathers, is offensive to nonbinary people? In all seriousness, not trying to start a flame war, why is that? Is a reference to hair offensive to a bald person?
The reason to replace an aggregate ‘brothers and sisters’ with ‘siblings’, ‘mothers and fathers’ with ‘parents’, or ‘boys and girls’ with ‘children’ is because for all of these the replacement suffices without calling attention to gender when it’s not necessary to do so.
There’s also an argument that the ‘X and Y’ phrasing makes the ‘X’ seem more important than the ‘Y’, or makes it seem like the ‘default’ - just a little, but with repetition the impression is reinforced. If there’s an alternative collective word to use, it avoids this ‘ordering’ issue with no real downside.
Note that all these arguments make sense in even if you consider gender to be a binary thing.
Using the perspective from the OP, it's a kids' book, using a couple of different synonyms might help them better understand what they're reading and not walk away believing that there's something wrong with their family or themselves.
I do now attempt to use the single-word non-gendered collective nouns in speech myself for the reasons I gave, and I think it’s a good idea to do so.
To discuss the edits to Dahl’s work: I would argue that for these ‘Xs and Ys’ examples he was probably just using the popular idioms of the time rather than choosing them to convey a specific meaning as you say. That would certainly be what I would’ve done, without much consideration, 20 years ago!
But that’s obviously not the case for all the edits that are reportedly being made.
The edits in aggregate do make me uneasy. I’m not sure how I’d feel if they were more limited.
Regarding the first occurrence being conceived as more important, it’s the reason usually females appear named first, a sign of courtesy to them. That was sorted out neatly long ago.
Yes, of course you’d need to be specific if it was important. I’d use ‘10 parents’ only if it wasn’t important.
Your example isn’t great though. Even if you assume binary gender for all parents in the group, you couldn’t replace ‘10 parents’ with ‘10 mothers and fathers’ because it’s unclear whether there are 20 people or 10. You’d need to be specific (‘6 mothers and 4 fathers’ or the like).
I don’t think your second paragraph refutes mine at all. I obviously don’t agree that it was ‘sorted out neatly long ago’. You could assume that from the fact that I’ve rethought my own behavior. This world would be a much worse place than it is if people never reconsidered whether the status quo from long ago was optimal.
[Edit: I see now that this comment was not on the same branch as the one where I said I’d rethought my own behavior from a default of e.g. ‘boys and girls’ to ‘children’, so I take back the sentence about you not seeing that. The rest stands though.]
I hate to be the guy that cries “1984,” but do we really have to completely neuter our language to avoid every imagined offense? Are there people out there who’s egos are so fragile that they can’t handle “gentlemen” coming after “ladies?”