Board Thread:Theories and Speculation/@comment-27541896-20160104042813/@comment-734582-20160107184609

QuakingStar wrote: They bred with very distant Hyuga relatives.. in order to keep the Byakugan 100% pure and in the bloodline. Preservation.. they do it at such controlled distance of relation that there are no genetic defects or illnesses. Safe, but still incest... Whether it's incest depends on the local law. For example, half-siblings breeding is not necessarily incest. First/Second order cousins are most often forbidden, third-order cousins is highly variable.

Secondly, inbreeding happens whenever sufficiently closely related people breed, regardless of whether it's incest. Defects can still happen, even with third (or more) order cousins. There was a program the other day where kids had a genetic anomaly, where a number of recessive genes had to be carried by both parents, causing abnormal finger length. It was statistically nigh-impossible, but still happened.

Thirdly, if the Hyuga are a sufficiently large clan, inbreeding to preserve the Byakugan can happen relatively safely. It seems the Hyuga and Uchiha maintained a strong clan structure precisely because of their Dojutsu, and may number in the thousands. Especially since, if losing their KKG is a real risk, they would be aware of the problems and necessities and would ensure a policy to protect their clan in both ways: maintaining genetic variance and their KKG.