This study comprises a genetic analysis of 139 members of an Hispanic population in the American Southwest. This population, little-known outside the Southwest United States, has a widely debated history. Its members identify themselves as Spanish-Americans, traditionally tracing their ancestry to Spaniards who settled in that area starting in 1598. In addition, a significant component of Jewish ancestry has been claimed for them, although this is currently disputed.

To test these claims, I typed Y-chromosomes and mitochondria for relevant genetic markers, sampled from the study population. DNA extraction and typing were accomplished by standard methods, and the results analyzed using various statistical tests.

Results from the genetic analysis show that the study population's Y-chromosomes are statistically indistinguishable from those of modern Spaniards, while the mitochondria are ∼80% Native American. This suggests that the founders of this population were essentially Spanish men, but mostly Native American women. There is some Jewish ancestry among the men, but no more than is found in modern Spaniards.