A genetic study of men in the early 2000s showed that many Hispanos of the American Southwest are descended from Anusim (Sephardic Jews who were forcibly converted to Roman Catholicism). Only Catholic Spanish were allowed to go to the New World with the exploration and colonial expeditions. Families first kept their secrets for protection and then out of habit. Michael Hammer, a research professor at the University of Arizona and an expert on Jewish genetics, said that fewer than 1% of non-Semites possessed the male-specific "Cohanim marker" or Cohen Modal Haplotype, which is prevalent among Jews claiming descent from hereditary priests. 30 of 78 Latinos tested in New Mexico (38.5%), were found to have Y-DNA with the Cohanim marker. Wider DNA testing of Hispanic populations has revealed between 10% and 15% of men living in New Mexico, south Texas and northern Mexico have a Y chromosome associated with the Middle East. Their history makes it most likely that they are Jewish rather than Arabic Muslims.