The first generations of Christians were Jewish. But very quickly they intermarried with non-Jews who adopted Christianity. Their descendents became part of the Christian population, and ceased to be part of the Jewish population.
The Jewish genetic markers identified by the studies are also found in non-Jewish populations, to a very small degree -- highlighting certain individuals as being partially of Jewish descent. Most of the "markers" are found on the paternal Y chronomose. I don't have the statistics in front of me, but I seem to recall that the Jewish markers are found on close to 90% of Jews, and roughly 3% of non-Jewish Europeans. That 3% would represent individuals who had a paternal male ancestor who was Israelite -- whether it was 100 years ago, or 1000 years ago.
But the 90% of Jews that have the same markings would that be of different races like Asians, Indians Pacific Islanders or does that matter?
that is roughly twice the rate that North American Caucazoids carry Amerindian DNA...last figure I saw was 1.7% but that was for Tennesseans who in my mind probably carry a bit more Creek and Cherokee blood than most Americans.