"Finding Your Roots with Henry Louis Gates, Jr." - DNA in the Sixth Episode

The sixth episode of Finding Your Roots with Henry Louis Gates, Jr., investigating the mixed ancestry of Robert Downey, Jr and Maggie Gyllenhaal, aired last night on PBS. These two actors not only share a profession, but both have a mixture of Eastern European Jewish ancestry as well as deep American roots. Because of these commonalities, I thought their stories worked well together. I was thoroughly entertained by this episode for three reasons: 1) I love Robert Downey, Jr., 2) I discovered that Maggie is my cousin through our shared 10th great grandfather John Lothrop and 3) The appearance of Bennett Greenspan, President of Family Tree DNA (or as Professor Gates called it "FamilyTreeDNA.com", which I am sure was much appreciated).

Bennett Greenspan on "Finding Your Roots with Henry Louis Gates, Jr."

Unfortunately, the DNA portion was only about five minutes long again this week (starting at 43:00), nevertheless it felt a bit more substantial to me than last time. I was happy to see a number of different tests featured: 23andMe's Ancestry Painting, FTDNA's Population Finder and mtDNA testing.

Robert Downey, Jr.'s "Ancestry Painting" from 23andMe

First, Robert Downey, Jr., whose father is half Jewish, was presented with a pie chart of his 23andMe Ancestry Painting, which breaks down a person's genetic ancestral origins into three populations - European, African and Asian. (Note - this test is included in the 23andMe Personal Genome Service and is presented as a chromosomal chart rather than a pie chart.) Dr. Gates has repeatedly stated that this test reveals "European, African and Native American ancestry", however I would like to remind readers that the Asian reference population simply "stands in" for Native American. 23andMe does this because the genetic makeup of the two populations is similar, but in reality, this is not quite the same as having reference samples from Native Americans and the two should not be confused with each other. For instance, a person could show Asian DNA on their Ancestry Painting, but one should not automatically reach the conclusion that they have Native American ancestry because they may have ancestors from China, Japan, Korea or any other Asian region. If a person has reason to suspect that they possess Native American ancestors and knows of no other Asian ancestry, then this test is useful for that purpose. As is typical of most people, RDJ guessed that his ancestry would be more "interesting" than it was and seemed disappointed to learn that his Ancestry Painting showed 100% European ancestry. As I have mentioned before, this actually encompasses all of Europe, including the Middle East, so it doesn't rule out RDJ's Jewish ancestry.

Robert Downey, Jr.'s "Population Finder" from Family Tree DNA

Next, Dr. Gates presented RDJ with what I believe was his Population Finder admixture from Family Tree DNA. (The PopFinder feature is included with the Family Finder test.) This test broke down RDJ's ancestral origins a bit more, showing that he is about 20% Middle Eastern or Jewish.  That is slightly under what we might expect for him with a father who is half Jewish, so his one Jewish grandparent may have had a little something else mixed into his/her ancestral origins.

Later, Dr. Gates sat down with Maggie to discuss her mitochondrial DNA (mtDNA) which is inherited straight down the maternal line, passed from mother to child as far back "as you can think" enthused Maggie. Maggie's mom is Jewish, so it makes perfect sense that Maggie's mtDNA has been inherited from one of four Jewish founding mothers who lived thousands of years ago. The voiceover explained, "Scientists have concluded that 40% of Eastern European Jews share genetic lineages that reach back two to three thousand years, remarkably to just four women...today about 3.5 million people descend from one of these four maternal ancestors." Haplogroup Project Administrator and genetic genealogist Vince Tilroe points out that Bennett Greenspan and Professor Gates were most likely speaking of mtDNA Haplogroups K1a1b1a, K1a9, K2a2a, and N1b when referring to the four Jewish maternal lines. These were identified in the 2006 study by Dr. Behar, "The Matrilineal Ancestry of Ashkenazi Jewry: Portrait of a Recent Founder Event".

Bennett Greenspan of FTDNA explaining Jewish DNA to Dr. Gates

Bennett further explained that Maggie had "hit the jackpot" with about 150 exact matches in Family Tree DNA's mtDNA database.  Bill Hurst, Administrator of the mtDNA Haplogroup K Project and a leading expert on this haplogroup, theorizes that if Maggie's mtDNA haplogroup is K, she likely falls into the K1a1b1a ancestral haplotype. Hurst explains that this haplotype's match numbers most closely coincide with the those that Bennett cited from FTDNA's database. At the HRV1/HRV2 level of testing, this haplotype now has 194 exact matches, but at the time of filming may have had closer to 150. He also notes that K2a2a is now called K2a2a1 due to recent discoveries. (There are three levels of mtDNA testing offered by Family Tree DNA which you can read about here.)

At the end of the episode Professor Gates discussed the question of "nature versus nurture" with his guests and asked Robert Downey, Jr. if he feels that his ancestral past has shaped who he is today. In answer, RDJ insightfully commented, "I don't see how it couldn't...it's informing you whether you're conscious of it or not, so probably better to be conscious." The episode ended with RDJ expressing his feelings about this experience with Dr. Gates, explaining that he felt that this was just the beginning of his journey of self-discovery.

I hope this show has also inspired all of you to begin (or continue) the journey into your ancestral roots. See you next week when we review the genetics of Samuel Jackson, Condoleezza Rice and Ruth Simmons. The television listing says that the show will be using DNA to "determine which parts of Africa their ancestors came from." That sounds promising!


I have been writing a review of the DNA testing used in each episode:
Week 1- Episode 1 & Episode 2 - Harry Connick Jr. & Branford Marsalis; Cory A. Booker & John Lewis
Week 2- Episode 3 - Barbara Walters & Geoffrey Canada
Week 3- Episode 4 - Kevin Bacon & Kyra Sedgwick
Week 4- Episode 5 -  Rick Warren, Angela Buchdahl & Yasir Qadhi