The Jews are a people defined by a shared covenant with God, not by their DNA. People can become Jewish through Halachic conversion by accepting 'Torah min haShomayim', i.e. that the Torah is Divinely revealed and binding as understood and applied by generations of Sages. A person with 'Jewish DNA' who comes from generations of Christians or Muslims is no longer Jewish and would need to convert in order to be accepted by the Jewish community.
Fire breaks out in Devira Forest, north of Be'er Sheva; four firefighting crews on scene (Haaretz)
from the article: Report: DNA tests support Zimbabwe tribe's claim of Jewish roots