Sperm Donor Unknown is the fascinating story about how a group of children born via sperm donation found their biological father, and each other, through the Donor Sibling Registry Website. It airs tonight on More 4 at 10 p.m. I've written here previously about Jeffrey Harrison and the 14 children he fathered in the 1980's as a way to supplement his income, in How many siblings do I have? For Donor 150's children, it's 14 and counting. The story of genetic connection isn't cut and dry; it involves real people and feelings, the exploration of identity, discovery and acceptance. This is what I will be watching tonight.