The researchers found a remarkably high level of Sephardic Jewish (19.8%) and North African (10.6%) ancestry in their large sample of Y chromosomes from the modern population. The Iberian Peninsula has a complex recent history that involves the long-term residence of these two diverse populations with distinct geographical origins and unique cultural and religious characteristics.
The large proportion of Sephardic Jewish ancestry does not fit with simple expectations from the historical record. "Despite alternative possible sources for lineages [to which] we ascribe a Sephardic Jewish origin, these proportions attest to a high level of religious conversion, whether voluntary or enforced, driven by historical episodes of social and religious intolerance that ultimately led to the integration of descendants," offers Prof. Jobling.
Everything we do shapes our genetics, as our genetics shape everything we do.