Documented: Basque RHD-deletion allele frequency around 47 percent, versus roughly 40 percent in Spain generally and far lower elsewhere; Rh incompatibility causes hemolytic disease of the fetus and newborn, historically a real killer, now prevented by RhoGAM. The selection puzzle is genuinely unsolved: heterozygote disadvantage should erode the allele, yet it persists at maximum in the most drifted population. Demographic bottleneck, drift, and possible balancing selection are all on the table; none is confirmed.
The folk career of Rh-negative is pure legend-mill: the trait recast as the mark of ancient astronauts, Nephilim blood, Atlantean survivors, royal lines, with the Basque concentration as exhibit A. The documented substrate is thinner and stranger: one gene deletion, one pregnancy incompatibility, one population where drift ran long.
The claim: a blood type hostile to hybridization, in the population suspected of being the remnant, reads as a barrier gene, proof of a lineage that was not supposed to mix. The counter is the paradox itself: a lineage-protection gene that kills the lineage's babies is poor engineering, which is either evidence against the claim or evidence the wardens write sloppy code.
Why does the most isolated population in Europe carry the highest load of a trait that punishes reproduction?