Jews, and Ashkenazi Jews in particular, are very genetically distinctive. A short and sweet way to think about this population is that they’re a moderately recent admixture between a Middle Eastern population, and Western Europeans, which has been relatively isolated due to sociocultural forces. As far as their inbreeding, well, here’s one recent paper, Signatures of founder effects, admixture, and selection in the Ashkenazi Jewish population: To explore the amount of genetic variation within the AJ and European populations, we first measured the mean heterozygosity. Surprisingly, we found a higher level of heterozygosity among AJ individuals compared with Europeans…confirming speculation made in one recent report and a trend seen in another…Although this difference may appear small, it is highly statistically significant because of the large number of individuals and markers analyzed, even after pruning SNPs that are in high LD. The higher diversity in the AJ population was paralleled by a lower inbreeding coefficient, F, indicating the AJ population is more outbred than Europeans, not inbred, as has long been assumed…The greater genetic variation among the AJ population was further confirmed using a pairwise identity-by-state (IBS) permutation …
Ashkenazi Jews are not inbred