Alondra Nelson delved into genealogy and DNA for more than a decade, and realized that genetic testing is being used to grapple with the unfinished business of slavery. It is being used for racial reconciliation, to establish ties with African ancestral homelands, to rethink citizenship, and to make unprecedented legal claims for slavery reparations based on genetic ancestry. Arguing that genetics offers a new tool for enduring issues, Nelson shows that the social life of DNA is affecting and transforming twenty-first-century racial politics.