Little brother, actually. And with how the volume version turned the school from co-ed into a girls' school, also the first male character to make an appearance.
And honestly I should've stewed on that translation a bit longer. The raw is "dislike of opposite-sex parents" but it sounded way too wordy and unnatural any way I wrote it out, so I tried to convey the same meaning in a more natural manner. I'm realising it influenced the meaning too much, which I'm not happy about.
I've edited the page to be more of a middle-ground even if I think it reads worse, but it more accurately reflects the original.