In the UK, any man who donates sperm through a licensed fertility clinic in the UK must waive his right to anonymity. Any children his donations produce can find out his identity when they turn 18.

When this law passed in 2005, donor numbers dropped by almost 90%. Men, it seemed, didn’t want to be known. They flocked instead to the online sperm donor market, where another kind of donor was looking for the opposite. They wanted to be known from the time a child was conceived, but the new law didn’t let them.

In this episode, Dr Aleks Krotoski meets Louise McLoughlin, a donor-conceived child whose biological father had been told by the clinics where he donated in the early 1990s that he would always be anonymous. She campaigns for the rights of donor-conceived children to know the identity of their genetic parent from birth.

Louise has a conversation with donor Alex, who’s looking for a recipient on Facebook to help him achieve his family dreams.