From The Guardian:

I don’t know why Teh Grauniad doesn’t capitalize “Jewish”…

DNA tests have been used in Israel to verify a person’s Jewishness. This brings a bigger question: what does it mean to be genetically Jewish? And can you prove religious identity scientifically? Oscar Schwartz When my parents sent their saliva away to a genetic testing company late last year and were informed via email a few weeks later that they are both “100% Ashkenazi Jewish”, it struck me as slightly odd. Most people I know who have done DNA tests received ancestry results that correspond to geographical areas — Chinese, British, West African. Jewish, by comparison, is typically parsed as a religious or cultural identity. I wondered how this was traceable in my parents’ DNA. After arriving in Eastern Europe around a millennia ago, the company’s website explained, Jewish communities remained segregated, by force and by custom, mixing only occasionally with local populations. Isolation and intermarriage

“intramarriage”

slowly narrowed the gene pool, which now gives modern Jews of European descent, like my family, a set of identifiable genetic variations that set them apart from other European populations at a microscopic level. … But still, there was something disconcerting about our Jewishness being “confirmed” by a biological test. After all, the reason my grandparents had to leave the towns and villages of their ancestors was because of ethno-nationalism emboldened by a racialized conception of Jewishness as something that exists “in the blood”. The raw memory of this racism made any suggestion of Jewish ethnicity slightly taboo in my family. If I ever mentioned that someone “looked Jewish” my grandmother would respond, “Oh really? And what exactly does a Jew look like?” …

In February of this year, the Israeli newspaper Haaretz, reported that the Chief Rabbinate of Israel, the peak religious authority in the country, had been requesting DNA tests to confirm Jewishness before issuing some marriage licenses. … Those being asked to take these tests, Farber told me, are mostly Russian speaking Israelis, members of an almost 1 million strong immigrant community who began moving to Israel from countries of the former Soviet Union in the 1990s. Due to the fact that Jewish life was forcefully suppressed during the Soviet era, many members of this community lack the necessary documentation to prove Jewishness through matrilineal descent.

And some of the Russian newcomers maybe aren’t Jewish through matrilineal descent. Ariel Sharon wanted to import a lot of voters who would identify with Ariel Sharon, and it helped make him Prime Minister of Israel.

I know that these days we are supposed to conceive of Russians as the opposite of Jews, but these days there are more than a few people in Russia, Israel, and Valley Village, CA who are mixtures.

… He explained that the Rabbinate are not using a generalized Jewish ancestry test, but one that screens for a specific variant on the mitochondrial DNA – DNA that is passed down through the mother – that can be found almost exclusively in Ashkenazi Jews. … In recent years, a number of high-profile commentators have appropriated these scientific insights to push the idea that genetics can determine who we are socially, none more controversially than the former New York Times science writer, Nicholas Wade. In his 2014 book, A Troublesome Inheritance: Genes, Race and Human History, Wade argues that genetic differences in human populations manifest in predictable social differences between those groups. His book was strongly denounced by almost all prominent researchers in the field as a shoddy incarnation of race science, but the idea that our DNA can determine who we are in some social sense has also crept into more mainstream perspectives.

You might think that the New York Times Science section is “mainstream,” but what Schwartz means by “mainstream” is “Jewish:”

In an op-ed published in the New York Times last year, the Harvard geneticist David Reich argued that although genetics does not substantiate any racist stereotypes, differences in genetic ancestry do correlate to many of today’s racial constructs. “I have deep sympathy for the concern that genetic discoveries could be misused to justify racism,” he wrote. “But as a geneticist I also know that it is simply no longer possible to ignore average genetic differences among ‘races’.”