Genetic studies on Jews related they were through IBD. Individuals within the Ashkenazi, Sephardi, and Mizrahi groups shared high levels of IDB, roughly equivalent to that of fourth or fifth cousins. All three groups shared many genetic features, suggesting a common origin dating back more than 2,000 years. The study did find that all three Jewish groups did show various signs of admixture with non Jews, with the genetic profiles of Ashkenazi Jews indicating between 30% and 60% admixture with Europeans, although they clustered more closely with Sephardi and Mizrahi Jews. In July 2010, Bray et al., using SNP microarray techniques and linkage analysis,
Ashkenazi Hebrew from Spain in 1492 (or before) the Sephardic pronunciation of the vowels became standard in all these countries, ironing out any differences that previously existed. This makes it harder to adjudicate between the different theories on the relationship between today's pronunciation systems and those of ancient times. Leopold Zunz believed that the Ashkenazi pronunciation was derived from that of Palestine in Geonic times (7th–11th centuries CE), while the Sephardi pronunciation was derived from that of Babylonia. This theory was supported by the fact that, in some respects, Ashkenazi Hebrew resembles the western dialect of Syriac while Sephardi Hebrew resembles the