To be fair, Ike is european.
they're one of the few vtubers that still roleplay so it makes sense to me, plus i never watched them before so i wouldn't know their voices are fake. biboo, luna and miko on the other hand are way too high pitch so i can't watch them which sucks cause i've heard biboo is sick at videogames (also the pacifier thing weirds me out)
Being the weeb that I am I have of course read up a bit about family culture in Japan and also seen a lot through anime (where I know it's mostly stereotypes, but stereotypes are based on reality somewhat at least). Family means everything in Japan and they often live together if they're able to, like all the way from grandparents to grown up kids.