User blog comment:Vafiz/A bit of genetics.../@comment-24850639-20170209182736

I remember the days when people used to swear up and down that Oda doesn't get scientific. I suppose that was before we met Caesar, and we still haven't even met Vegapunk. Now add in this "lineage factor" business that we learned about, and I think you are on to something. I do think genetics will play a role for that alone, but probably not exactly this way with the whole dominant/recessive business. I think he'd just keep it simple, and just say someone's either born with it or not.

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Genetics

Dominant and Recessive traits are based on something called Genotype, which is represented by something called alleles. Alleles are generally represented by letters - Capital letters indicate a dominant trait, lowercase letters, a recessive trait. A genotype consists of at least 2 alleles, and 1 dominant allele is all it takes for the dominant trait to manifest itself. So lets use your example with Conqueror's Haki, saying that having it is recessive. Therefore, not having it is dominant. We'll represent it with the letter A:

Somewho doesn't have Conqueror's Haki would have a genotype of "AA", or "Aa". Someone who does have Conqueror's haki could thus ONLY be "aa". If 2 "AA"s get together, there is zero chance of Conqueror's Haki. If 2 "aa"s get together, there is a 100% of Conqueor's Haki. If an "AA" gets with an "Aa", there is still a 0% chance of it, because all outcomes will be either "AA" or "Aa". If 2 "Aa"s get together however, there is a 25% chance of Conqueor's Haki (50% chance the kid will be Aa, 25% chance of AA, 25% chance of aa)

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This is already pretty much debunked, because it implies that for every conqueor's haki user in the world, BOTH of their parents had to have it. Granted, we don't know everyone's parents, but I'd be hard-pressed to believe that Donquixote Homing or Portgas D. Rouge had it lol. But again, I do still think you're onto something with genetics, and it being part of a person's "lineage factor". I just think its one of those abilities that can "skip" generations, and/or is pretty much random in terms of who gets born with it.