Although Jews usually, but not always, share a common gene pool, they are not a race because any non-Jew 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 really not about who is a Jew, but who is a rabbi.

But what about the Jewish law that defines a Jew as one who is born of a Jewish mother. Isn’t this evidence of Jewish racial thought?

For Christians, who believe that only adult baptism by personal belief (Protestant), or infant/child baptism by an authorized church sacrament (Roman Catholic and Eastern Orthodox) makes one a Christian, it seems strange that children of any Jewish mother are Jewish; even if the father was not Jewish and they know little or nothing about Jewish beliefs.

But Muslim law says the same thing: children of any Muslim father are Muslim even if the mother was not Muslim.

In truth, Christianity is an unusually disembodied religion compared to Judaism and Islam and there is no reason other religions should be equally disconnected from the ethnic body of their believers.

When it comes to Jews who are non-religious or even anti-religious, they are considered secular or cultural Jews, unless they as adults convert to another religion.

It is true that Orthodox Jewish law still considers even apostates to be Jewish, but that is 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, so Orthodox law still gave all of them the benefit of the doubt.

Some Jews today who have converted to Christianity as part of 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 Jewish State located 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.

Being a faithful part of the Jewish community in terms of group connection and religious action is more central to being Jewish than adhering to credal statements. That is why 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 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 of Jews 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. Most in part, but none totally.

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, Jews have almost always, when they were free to do so, 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.

In a previous genetic analysis, the researchers showed that modern-day Sephardic (Greek and Turkish), Ashkenazi (Eastern European) and Mizrahi (Iranian, Iraqi and Syrian) Jews that originated in Europe and the Middle East are more related to each other than to their contemporary non-Jewish neighbors, with each group forming 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.

The current 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.

The 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 endogamy, or 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 are descendants of ex-Jews from previous generations who are now returning to the Jewish People, and bringing in some lost Jewish genes as well as some non-Jewish genes with them.