DNA and Our Twenty-First-Century Ancestors

Some of my ancestors might live just up the street. They are the people who own the black camper van with a decal brandishing the words “Irish Pride.” I pass their house on my walks, a little unsure where ethnic importance might blur into white nationalism even in the hills of Oakland, California. The sticker, a simple bloc design in green and white, joins the two potentially menacing terms in a crossword. The middle I hinges them in a calm, clover-colored Celtic cross that sends my brain thinking of meadows to flee the idea of possible racial hatred. Lightly freckled, with age-bleached red hair like my mother, the man recently waved to me from one of several cars parked on their auto-filled lot, where the couple has taken to hanging out on sunny afternoons during COVID-19.

One tribe down. Hundreds, possibly thousands, more to go.

The next most obvious might be the Yoruba, somewhere among the people on my dad’s side. One, who arrived from Lagos a few years ago, is a friend who lives down the hill in the...