He's apparently an anomaly.
Conan O'Brien stopped by The Late Show with Stephen Colbert for a chop up with his fellow comedian. During the conversation, Conan revealed some fun facts about his genetics. The entertainer recalled requesting a DNA test like many people have been doing thanks to affordable kits available online. Conan accepted his doctor's offer to process his DNA to learn about his heritage. The test yielded surprising results.
“Two weeks later [the doctor] called me up,” O’Brien, 55, explained. “He said, ‘I have never, ever, ever had a DNA test like this before and I’ve been doing this for 10 years.’” Apparently, he's 100% Irish. This is surprising considering that Irish people who actually live in Ireland have a more diverse genetic makeup “You will find out that the most Irish looking people are like 86% Irish, 94% Irish,” he remarked. “The Lucky Charms leprechaun, true fact, 11% Spanish.”
His doctor shed light on the results, simply stating: "That means you're inbred."
O'Brien also said his experience with puberty was unusual, earning him a "disproportionate" body. "When I was 14-years-old I had a massive growth spurt. I went to 6"4 overnight," he said." My legs grew and grew and my torso never did. I have the legs of an NBA center and the torso of a little girl."