Here’s how I view it:
Most of the Loki variants came from the original multiverse (before Immortus and the TVA came along and pruned everything). The further back the timelines diverged, the more different things will be in the present.
I probably shouldn’t be quoting DC here, but there’s a quote in Justice League: Crisis on Two Earths that explains it perfectly: “Some [timelines are] so similar to each other that you could spend a lifetime searching for any distinction. Others so radically different, they defy comprehension.”
So depending on how far back you go, the different Lokis likely have different genetics. They’re still Loki, even though they might not look like him. From the more recently diverging timelines, you have the other Tom Hiddleson Lokis (Time-Traveling Loki, Soccer Loki, Norse Troll Loki, President Loki) or Lokis that look like him at different ages (Kid Loki, Classic Loki).
Meanwhile, in earlier branching timelines, you could have a Loki who’s blonde and female (Sylvie), one where he (and presumably the other Asgardian royals) are black (Boastful Loki), and one breaking off millions of years earlier where Asgardians are sentient alligators for some reason (Alligator Loki).
So if the earlier branching versions have different genetics, it wouldn’t really be incest. Narcissistic maybe, but not incest.
