
A study by Duke University's Center for Human Genome Variation found that
"...even subjects with a single Jewish grandparent can be statistically distinguished from those without Jewish ancestry. We also found that subjects with Jewish ancestry were slightly more heterozygous than the subjects with no Jewish ancestry, suggesting that the genetic distinction between Jews and non-Jews may be more attributable to a Near-Eastern origin for Jewish populations than to population bottlenecks."
"Near-Eastern origin" indicates that the link between them and the Ancient Israelites is quite real. The ancestry of Ashkenazi Jews traces itself back to formation of the Kingdom of Israel. Last names such as Levi and Cohen, indicate a relationship to Jewish priests and rabbis. The fact that many Ashkenazi Jews have a surname with the suffix of "-Berg"(meaning mountain in German) is due to their attempts to blend in with populations in Germany. Essentially a nomadic people for much of history, the Jews are an interesting case for anyone interested in tribal ancestry.