We finally made our way to a theatre to see “12 Years a Slave” today. Throughout this gripping, gut-wrenching film, this ran through my head: “These are my cousins. These are my cousins. These are my cousins.”

My 23andme Relative Finder is filled with matches who know only that their families lived in Mississippi or Louisiana. All my African-American lines are upper South, rooted in Virginia and North Carolina. The link is obvious. My DNA matches are the descendants of the mothers and fathers, aunts, uncles, cousins, and siblings of my ancestors, sold down South in America’s domestic slave trade. The connections are nearly impossible to recreate, the names lost to time, but I take comfort in the fact that the bonds remain detectable in blood and bone.