I love it when they focus on the class rep and her family. I find them the most interesting since they're the only mixed family we know of. I really wanna know the genetics behind it, especially since class rep only has angel characteristics, the triplets with only long eared characteristics and sue-chan actually showing both. It makes me wonder which side is actually dominant or recessive. They've never said if the triplets and class rep were siblings by marriage so I assume they were all born from the same parents.
Yeah, I'm almost certain the Class Rep refers to being around the Chi triplets pretty far back. And given how much she looks like Sue, it makes sense that they're all blood-related.
As to other mixed race characters... Nozomi's cousin Akira (from Chapter 40) looks uncannily like her, except for the fact that she has cloven hooves and horns, which she inherited from her mother (meaning that the uncle is a Divel). So Akira and Sue both exhibit racial traits of both parents. But you're right, it does seem that there's a larger percentile for one parent's genes to end up being recessive in the offspring.
Though this seems to happen enough that the Government has programs set up to provide support services to cross-species children who suffer from medical issues. Kyouko even references this in Chapter 00 (complete with a cut-away to an ad in the newspaper), so there seems to be some cultural awareness of the issue.
While I'm like 80% sure they were all born from the same parents, the possibility of them having separate parents could still exist. Class rep's mom could have married the Chi triplets' father when they were really little, resulting in Sue as the only mixed sibling. This little fact bothers me a lot so I hope they talk about it eventually haha. Also they rarely mention their mom and I'm curious about her. It's probably a touchy subject though which is why it's never brought up.
Oh yeah I completely forgot about her. Yay more mixed characters! Rereading the chapter, I hope they bring her back again too.
Because it's supposed to mirror our own society, I think it would be more surprising if there weren't any mixed families. Maybe they'll have a chapter explaining cross-species' rights. I'm sure that, like our society, interracial/species marriages were probably frowned upon in the olden days. The genetics behind it fascinates me and I really hope they elaborate on it more. Like why do children mixed with centaurs have a higher birth defect? Which traits of certain species mix well and don't mix well? Maybe the traits that stay will help for evolution of the human species and shed light on how the evolution of each species came about. I know they touched upon evolution lightly and that it's "still being researched," but yeah so many possibilities. I really love the world building and just love the little facts about the universe that get revealed with each chapter.
This has actually got me thinking that maybe Sue really is the only mixed sibling. If cross-species children have a higher chance of suffering from medical issues, it explains why she's a really weak child. Ok now I'm back down to being 50/50 again on whether or not class rep and the Chi-triplets are blood related or not >_<;;