Although Jews usually, but not always, share a common gene pool, they are not a race because anyone who converts to Judaism will be recognized as being Jewish by all those rabbis who share a commitment to the same denomination of Judaism as the rabbi who did the conversion.
The dispute, in terms of conversion, is not really about who is a Jew, but who is a rabbi.
When it comes to Jews who are non-religious or even anti-religious, they are considered secular or cultural Jews, unless they are converts to another religion.
Orthodox Jewish law still considers even apostates to be Jewish, because for over fifteen centuries Jews were frequently subjected to persecutions and forced conversions, which meant that thousands of Jews who were baptized still believed in the One God of Israel.
Some Jews today who have converted to a Protestant Fundamentalist denomination call themselves “Jews for Jesus” or Messianic Jews; but almost all non Orthodox Jews think they are simply mixed up.
Like most nations, Jews have a national language, a shared history, which is much longer than most nations, and a style of cooking and thinking that is as distinctive as that of many other nations.
What they have lacked for most of their 4,000 year history is an independent State in one geographical area. However, states come and go (Yugoslavia) and go and come (Poland and Israel) so having a state is not the most important aspect of being a nation.
More important is that the majority of Jews do not view “Jews for Jesus” or Messianic Jews as belonging to the Jewish community.
The answer to the question of what are Jews is that since Judaism and the Jewish People are so deeply intertwined they cannot and should not be separated.
Individuals Jews act in all kinds of ways, but the historical community is a blend of Jews by birth (genes) and Jews by belief, behavior and belonging.
New genetic studies show how over the centuries many non-Jews have entered the Jewish community and many Jews have, voluntarily or not, left the Jewish community.
Today we can answer the complex question: are all present day Jews really the biological descendants of the Jews who inhabited the Land of Israel 3.000 years ago?
The answer is: Yes and No.
Genetic analysis does support the historical record of Middle Eastern Jews settling in North Africa during Classical Antiquity, actively proselytizing and marrying local populations, and, in the process, forming distinct populations that stayed largely intact for more than 2,000 years.
The study, led by researchers at Albert Einstein College of Medicine of Yeshiva University, was published online August 6, 2012 in the Proceedings of the National Academy of Sciences.
“Our new findings define North African Jews, and enhance the case for a biological basis for Jewishness,” said study leader Harry Ostrer, M.D., professor of pathology, of genetics and of pediatrics at Einstein and director of genetic and genomic testing for the division of clinical pathology at Montefiore Medical Center.
However, as anyone who has been to present day Israel knows, Jews come in many shades and looks. This is because even in the diaspora, and even against the will of the ruling religious authorities, some Jews have almost always proselytized their neighbors, and quietly welcomed converts into the Jewish community, even against the formal rules of medieval rabbis.
That is why most Jews in different geographical locations tend to look similar to the local majority after several generations.
The rabbinical rule that one should not refer to any Jew’s convert status is evidence of the desire of Jewish leaders to keep proselytizing activities secret from the ruling religious authorities.
This is why very few Yeshivah students know that Rabbi Akiva ben Yosef HaGer was the son of a convert to Judaism.
Now what can genetic analysis tell about Jewish genes today?
In one major genetic analysis, researchers showed that modern-day Sephardic (Greek and Turkish), Ashkenazi (Eastern European) and Mizrahi (Iranian, Iraqi and Syrian) Jews who originated in Europe and the Middle East, are more related to each other than to their contemporary non-Jewish neighbors.
But each group also formed its own cluster within the larger Jewish population.
Further, each of the four geographical groups genes, demonstrated Middle-Eastern ancestry, plus varying degrees of inclusion of converts to Judaism from the surrounding populations.
This is true even though two of the major Jewish populations — Middle Eastern and European Jews — were found to have diverged from each other approximately 2,500 years ago.
A newer study which extended the analysis to North African Jews, the second largest Jewish Diaspora group found that they also were more related to each other than to their contemporary non-Jewish North African neighbors.
This study also included members of Jewish communities in Ethiopia, Yemen and Georgia. In all, the researchers analyzed the genetic make-up of 509 Jews from 15 populations along with genetic data on 114 individuals from seven North African non-Jewish populations.
North African Jews exhibited a high degree of marriage within their own religious group in accordance with Jewish custom. Ethiopian and Yemenite Jewish populations also formed distinctive genetically linked clusters, as did Georgian Jews.
Yet some converts to Judaism, and their genes, have always entered the Jewish gene pool.
In the west today many converts to Judaism are descendants of ex-Jews in previous generations who are now returning to the Jewish People, and bringing many non-Jewish genes with them.
This unusual path of religious conversion resulting from reincarnation is a special aspect of Kabbalah: the Jewish mystical tradition.
Unlike Buddhism and Hinduism, Kabbalah does not teach that reincarnation (gilgul) occurs over the course of millions of years to millions of different sentient species.
According to Kabbalah, only the souls of self conscious moral creatures like human beings, reincarnate; and they reincarnate only when they have not fulfilled the purpose of their creation.
Since Judaism is an optimistic religion, most Kabbalists teach that most people can accomplish their life’s purpose in one or two lifetimes.
A few souls may take 3-5 lifetimes or more. The bright souls of great religious figures like Moses or Miriam can turn into dozens of sparks that can reincarnate several times.
The tragic souls of Jews whose children have been cut off from the Jewish people, either through persecution or conversion to another religion, will reincarnate as one of their own no longer Jewish descendants.
These descendant souls will seek to return to the Jewish people. A majority of people who end up converting (or reverting) to Judaism and the Jewish people, have Jewish souls from one or more than one, of their own ancestors. However, the genes they bring in are mostly from their non-Jewish ancestors.