Forty-six-year-old Mel only found out as a teenager that she was conceived using a sperm donor. Now she wants to see if she can find her biological father’s identity by decoding her DNA - and discovers far more than she ever expected. Fi always knew she was adopted. What she didn't know until later in life was that her father murdered her birth mother. Fi wants to know if it is possible to inherit a 'murder gene'. Bahaa escaped the war in Syria but now wants to know if he carries a potentially deadly mutation in his DNA.