Taking a DNA test might yield some surprises about your heritage; a recent survey shows that more than a quarter of those who use mail-in DNA tests end up learning about close relatives they didn’t know about. But it’s not always happy or comforting news. Rita Braver talks with people who have met siblings for the first time, and with members of a support group for those who suddenly discover they have different biological parents from those who raised them. She also finds out how employees at 23&Me get special training to counsel people who’ve made shocking discoveries about their families.