Board Thread:Episode Discussions/@comment-1181222-20170712100345/@comment-28518855-20170712131045

It's not clear if the Otsutsuki had Byakugan before Kaguya. The way the Red Pills work, it seems that only the higher-ups of the Otsutsuki have chakra and possibly the Byakugan. Even so, yes all Moon Otsutsuki are related to Hamura because they have the Byakugan. Enough time has passed for all of them to be related even if initially not everyone was.