A: When your kid is ready to process concepts like incest, can handle realistic violence and gore, and won't be traumatized by nudity and explicit sexuality.
My oldest is 17 and could probably handle it (but doesn't want to

). My 13-year old would want to watch because FOMO, but isn't emotionally or mentally ready. The older kid will come to me with questions and thoughts. The younger doesn't verbalize their feelings and tends to act out. It's not just their age; the decision has to consider their personality and abilities. A lot of this also depends on the kind of relationship you have with your kid(s) and what sort of media they've already shown an ability to handle. If Harry Potter freaks them out, well, this isn't for them. If they get squeamish about blood or violence, this is a bad show for them. If you can't have open, honest dialogue about sex, or they don't have a trusted adult they can turn to for questions and discussion on sexual topics, there's too much sexuality in this show for them.