My great-great-great-grandfather Lewis Henderson has no known patrilineal descendants, but his brothers James Henry and John do. About a year ago, I reached out to my cousin C., who is in the James Henry line, to ask if he would test with 23andme. After some hesitation, he agreed.

C.’s results returned in a few weeks, and I called him to share the details. “So, am I a Henderson?,” he blurted. I laughed: “Of course you are, crazy!” C. is the spitting image of his father, but — his parents had not married. Hearing that Hendersons (including my father and K.H.) were among his top matches and that he shared the same haplogroup as other patrilineal Hendersons had vanquished lingering uncertainties that I had not even known C. harbored.

The core of the Henderson family is deeply religious, and our reunions feature a farewell prayer breakfast at the host hotel. C., who is an ordained Baptist minister, rose to deliver a mini-sermon to those gathered. “Blood done sign my name,” he said. “Blood … done sign my name.” You may know this traditional gospel song, whose lyrics speak to the belief in the redemption of sinners through the blood that Jesus Christ shed on Calvary. C. preached on salvation Sunday morning, but he also invoked this metaphor in a different way. With a simple DNA test, C. was free from doubt and able confidently to claim his place among the Hendersons. Blood had signed his name on the roll books of our family.