Can't really have consanguinity problems if your genes are divine perfect health. If anything, it's the introduction of that world's inferior genes from vampires, angels and other species that will threaten the longevity of the Village Chief clan.
@birdulon correct, if he's in perfect health it would not really be a issue of increased chance of genetically defects. Since 0 multiplied by a thousand is still 0.
But culturally it might become a issue if people think fucking half siblings are okay because then later generations wont be alarmed when it happens with someone that don't have perfect health have sired such.