Why is Ashkenazi Jewish ancestry "often complicated to unravel"?
February 10, 2024 10:47 PM   Subscribe

I was reading this article in the LA Times (CW: decapitated murder victim and gated article) and it said that it was difficult to discover who the murder victim was through DNA and constructing family trees because she was an Ashkenazi Jew. Why is that more complicated than anyone else?

Here is the quote for those who can't access the article or don't want to read it:

“Our team worked long and hard for this identification,” said Missy Koski, the team leader of the investigation. “Ashkenazi Jewish ancestry is often complicated to unravel. When we brought in an expert in Jewish records and genealogy, that made a huge difference.”

It never explains why it is complicated. Google isn't helping. Help?
posted by Toddles to Science & Nature (8 answers total) 4 users marked this as a favorite
Having done some genetic genealogical testing for my own purposes (and I am an Ashkenazi Jew) - my genealogical research assistant mentioned that there is a significant amount of endogamy in the Ashkenazi population, which makes sense because if, historically, Jews were only breeding with Jews, eventually, you end up breeding with people you are related to...
posted by birdsquared at 10:59 PM on February 10 [3 favorites]

According to this article, it's about genetic drift.

Wikipedia says: "Collectively, Ashkenazi Jews are less genetically diverse than other Jewish ethnic divisions, due to their genetic bottleneck."
posted by lulu68 at 10:59 PM on February 10 [1 favorite]

My first guess is that the Ashkenazi Jewish community is deeply in-bred over many generations. As a result, any two people may have shared dna from multiple ancestors so it looks like they have a degree of relatedness that is much closer if you assume that all of the shared DNA comes from just one common ancestor.

For example, my DNA ancestery search shows more than sixty second-third cousins. I know all of my second cousins and some of my third cousins. There have been four out of the sixty reported "close cousins" where I can find a relationship. The others don't share any commonalities that I can find. So most of those sixty people where DNA testing shows us as second-third cousins are probably multiply related to me - a combination of maybe a fourth cousin on my grandfather's side and sixth cousin on my grandmother's.
posted by metahawk at 11:06 PM on February 10 [2 favorites]

23andMe estimates me as 100% Ashkenazi Jewish. I have thousands of DNA relatives on 23andMe and most of them share around 1% of my DNA and are estimated to be second or third cousins, but they are actually more distant than that. I know my family tree fairly well and don’t know these people or even, in most cases, recognize their last names. In many cases the DNA I have in common with another Ashkenazi Jew is actually partly from my mom’s side and partly from my dad’s, so we must have multiple longer-ago ancestors in common rather than one great-grandparent or great-great grandparent.
posted by needs more cowbell at 11:06 PM on February 10 [3 favorites]

As well as the above DNA-related issues, Jewish ancestry can be further complicated by incomplete or (accidentally or intentionally) lost records due to various pogroms and the Holocaust, Anglicized or mistakenly recorded names, poor access to census recording, and so on. I've been researching my largely Ashkenazi family tree and some of my family members have four or five different variations on their name recorded across various official documents, which is further complicated by the fact that there might be another four or five people with the same name living in the same area. There's almost nothing from before the early 1900's and it's not easy to pick out who actually might be an ancestor and who might just be another Moishe from across the village.

This correlates with the findings of the team investigating the murder victim:

"Because the cousins were so distant and had such common names, investigators had to build massive family trees in order to find common ancestors with their Jane Doe. They had to go back eight generations in their attempt to identify the woman. They even had to track down Eastern European genealogical records to aid in their research."
posted by fight or flight at 3:06 AM on February 11 [10 favorites]

fight or flight: t's not easy to pick out who actually might be an ancestor and who might just be another Moishe from across the village

Yeah, in addition to records being lost or destroyed in pogroms and the Holocaust, names aren't always a great way to track ancestry. I have one of the more common Ashkenazi surnames and I share my last name with many, many people who are not related to me.
posted by capricorn at 4:48 AM on February 11 [1 favorite]

Actually, there have been several genetic bottlenecks in Ashkenazi history, beginning with the exodus of Rhineland Jews to East Europe during the Black death plagues and subsequent pogroms against the Jews of France and Germany. In the 15th century there was a spike in Middle Eastern Mizrachi Jewish genes which may have been attributed to Jewish men drafted into rabbinical positions from the Iraqi Jewish communities to replace educated men killed in the previous century, and Sephardic refugees from Spain (many classic Ashkenazi family names are calques on Ladino names: Alpert < al Perez) . The Khymelnytsky Massacres in the 17th century decimated Galician and Ukrainian communities, and led to the migration of those remnants to places like Hungary and Romania. And then we have the Holocaust, which nearly obliterated the Ashkenazi population of Europe.

Given the popularity of home genetic testing these days, the experience often less exciting for Ashkenazim. One of my buddies took a 23 and Me test a few years back, and joked "Wow! According to this I'm actually 20 percent Litvak!"
posted by zaelic at 3:38 AM on February 12

There's also the name changes that come with immigration - my bubbe immigrated as a two-year-old and decided as an elementary school student to anglicize her given Yiddish name. Her passport is a photo of her mom and all her sisters with her as a serious faced baby in white, with her mother's name hand written across it. Who knows what her official documents say about any of it.
posted by Lawn Beaver at 11:43 AM on February 12

« Older Where to start reading The Peripheral if you've...   |   Kdrama and animal cruelty? Newer »

You are not logged in, either login or create an account to post comments