But let's use more specific examples: Parent A (mother) is Catholic and Parent B (father) is Episcopalian...kids are brought up Catholic, but then one becomes a teenager and thinks "Wait my dad's church is so much better, it's basically the same thing except it's fine with gays and has female priests, so I'm just going to be that instead" and then completely sheds all vestiges of their Catholic identity and just tell their parents they're going to say they're Episcopalian from now on....even if the father was a purely nominal and non-practicing Episcopalian to begin with, it's the politics and fitting their identity that attracted them, not the "culture" or whatever. Because I know THAT reason gets some people here really triggered for who knows what reason (and as I've noted this is like the one place on the Internet where that's the case, it's completely alien to Reddit and I can't even find it on the ultimate cesspool of hot takes: Twitter), so is it OK in this example because they have some family and ethnic background regardless? And if it's OK is it also OK for someone from a fully Catholic family to do this?
Liberal Catholics converting to ECUSA is a widely accepted tenet of cultural Catholicism.
That said, your scenario here doesn't really make any sense — it is
always, at some level, about the culture. That's why you get Catholics specifically converting to the Episcopal Church, it's a place that is culturally (and liturgically, etc) comfortable for Catholics to a degree that many other denominations are not.