Tech: The host of PBS' 'Finding Your Roots' explains how he traces family trees for celebrities

According to Dr. Henry Louis Gates Jr. it can take anywhere from a couple of months to a year to trace one family tree on "Finding Your Roots."

• Host of PBS' hit series "Finding Your Roots" Dr. Henry Louis Gates Jr. helps different celebrities trace their family tree.
• Dr. Gates has helped trace the family trees of celebrities like Scarlet Johansen, and Larry David.

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When Dr. Henry Louis Gates Jr. isn't teaching classes at Harvard University, he's spending his nights and weekends working on his wildly popular PBS series "Finding Your Roots."

The self-proclaimed "genealogy Santa Claus" creates family trees for celebrities like Scarlett Johansen and Larry David on his series, which has now entered its fourth season.

Dr. Gates spoke to Business Insider, about the work that goes into crafting a family tree on "Finding Your Roots," how he learned that Larry David and Bernie Sanders are related, and why he thinks people are so fascinated with their ancestry.

Dr. Gates says it can take anywhere from a couple of months to a year to trace someone's family tree on the series, and that the process is a combined effort.

The "Finding Your Roots" production research staff combs through records and public documents, while the famous Broad Institute at Harvard analyzes DNA independently.

And it was through DNA analysis that Dr. Gates made one of his most striking discoveries on the series: comedian Larry David and politician Bernie Sanders are related.

"We're sitting there fantasizing, going, 'Wouldn't it be wild if we found out they were related?' And everybody goes, 'Man that would be too much.' And then we found out they were," Dr. Gates said about the discovery.

The promotional clip of David and Sanders shocked to learn that they're genetic cousins went viral at the beginning of October - in large part because David has recently become known for his spot on Sanders impersonation on "Saturday Night Live."

The diligent work of Dr. Gates and his staff is one of the primary reasons that "Finding Your Roots" now has an expansive list of celebrities dying to be on it.

People are intrigued by the past, and according to Dr. Gates no one really knows much about their own.

But beyond curiosity, Dr. Gates finds that anxiety about the future often propels people to look into their past.

"People have so much anxiety about the future, so they want to anchor themselves in the past, and not by taking a course in world history, or American history, but in taking the course of their own family history," Dr. Gates said.

Although it's unclear if Dr. Gates' guests on "Finding Your Roots" are able to quell their anxieties about the future, Dr. Gates said that they almost always end up having a far more comprehensive understanding of the struggles their ancestors endured.

According to Dr. Henry Louis Gates Jr. it can take anywhere from a couple of months to a year to trace one family tree on "Finding Your Roots." Read Full Story