Board Thread:Spoilers/@comment-28118206-20160403030006/@comment-36342671-20180803135944

I'm assuming like all recessive traits the natblida blood isn't always visible in the carrier's phenotype. The same way that someone with blood type A can have a child with blood type O if both they and their partner carried the recessive 'i' allele. This way if someone whose ancestor was a natblida still carries this allele in their genotype, they may have a kid that's a natblida. Also, not all natblidas fight to become commander as it can be assumed not all families want their child to fight to the death.