According to family lore, when their business needed money my great-grandmother Charlotte Langermann Thannhauser, on my German Jewish side, fixed up her sister Lina with her husband’s half brother in order to get Lina’s dowry invested in the family enterprise. Not such an uncommon occurrance. I was able to convince Lina’s great-granddaughter on the straight maternal line to test at 23andme. She is almost doubly my third cousin, sharing DNA from the Thannhauser and Langermann lines but not Engel.