COEUR D’ALENE, Idaho — Sue Docken’s start in life, in 1951, with a no-questions-asked cash adoption at the hands of a midwife, had strong elements of the crime scene that it was.

Her adoptive father was told to stay in the car and keep the motor running. His wife went into a nondescript office building in Butte, Mont., where she met with the midwife, Gertrude Pitkanen, and was handed the hours-old infant and the afterbirth, offered a peek through a curtain at the young mother lying in a bed, and told to leave. The afterbirth was thrown out the window on the drive home, Ms. Docken was later told by her adoptive parents, who paid $500 for her that day.

Ms. Docken is one of about two dozen people, mostly in the West, belonging to a self-styled club whose members call themselves “Gertie’s Babies.” (More are believed to be out there, unknown perhaps even to themselves.) Their lives are diverse, connected only by a common thread, Ms. Pitkanen. Sometimes known more grandly as Gertrude Pitkanen Van Orden, she delivered and sold babies, performed abortions — and mostly evaded legal consequence — in Butte from the 1920s through the 1950s. The secrets she left have fueled a search for origins and answers, in some cases lasting decades.

Now, some of the back stories of the Gertie’s Babies have started to come to light through DNA-matching research sites like Ancestry.com and 23andMe.com, to which people can send a cheek swab in hopes of finding a match with relatives who have also submitted a DNA sample. Tales have emerged of desperation, betrayal and secrets taken to the grave, but also of joy and newfound connection, like Heather Livergood’s.