To my understanding Ashkenazi Jewry did regularly get influxes of new genetic material to the point where they are not easily distinguishable for eastern europeans. They also from my research have a higher then average level of "royal diseases" like hemophilia. Considering that the originators were only a few million people at best and that these breeders are likely distant family relations(the ones Suit wanted were all grandchildren of Spook) inbreeding could easily become a problem.