Stacey Dooley helps answer life-changing questions through the power of DNA. A set of adopted triplets want to discover their ethnicity, and gene therapy could stop Leo going blind.

This time, Stacy meets 31-year-old Duri, who fears she may carry a potentially fatal genetic mutation and wants to test her DNA to see if she could suffer from the same disease as her mother. Elsewhere, a woman who was adopted when she was just six-months-old wants to use DNA technology to finally uncover information about her ancestry.

In this episode, Stacey meets 75 year-old Bill, who grew up without a father. Born at the end of World War II, Bill's mum fell in love with his dad, who was an African American GI stationed at her local Loughborough airbase. He went back to America at the end of the war and she never heard from him again - the only information Bill has ever had about his father is the name written on his birth certificate. Now Bill wants to know if analysing his DNA might be able to tell him what happened to his dad - and if he has any living relatives in the US.