According to the New York Times, a new study of mitochondrial DNA has determined that European Jews are descended from four mothers. (No, not the Biblical Sarah, Rebecca, Leah and Rachel.)
It appears that these four women, who lived somewhere in the Middle East roughly two to three thousand years ago, are the grandmothers of some 40 percent of Ashkenazi Jews, which would include moi. This is an interesting complement to the Y-chromosome research from a few years ago (also mentioned in the article) that showed many Jewish men around the world were of Middle Eastern descent.
Of course, some scientists claim that the mitochondrial evidence is not statistically significant, so who knows? What we do know is that Jewish mothers are very important, as anyone who has had one can tell you.