"I just want to know who I am," says former sprinter and gold medallist Jamie Baulch who has been searching for his biological father in Nottingham.
The Olympic athlete was born in the city and adopted by a couple from South Wales when he was six months old.
Until 2014 he did not know his birth parents, or that his father was Jamaican, which he said could explain his speed.
Now, 43, Jamie has taken his search back to Nottingham.
His journey has been followed by cameras for a BBC documentary.
"I didn't think I would ever find any information on my father," he said.
"You never know what you are going to find but the reason why I can do this is because my upbringing has been fantastic. There was never confusion, but I wanted to find out more about who I am.
"I wanted to know where I got my running ability from."
She told him his father was called Leonard, in his 60s, lived in Castle Boulevard, Nottingham and liked football.
Teresa was 19 when she fell pregnant but said her parents disowned her and Jamie's dad left her, so she gave him up for adoption.
She died last month after a battle with cancer.
The latest documentary sees Jamie visit Caribbean groups in Nottingham and carry out an interview on a local radio show in the hope of finding Leonard.
"I feel I'm Welsh through and through but knowing I'm born in Nottingham and going round the streets was different," he said.
"The people were so helpful and that meant a lot to me. There was a lot of tears, a lot of fun and a lot of sadness too."
Being Jamie Baulch: The Search For My Birth Dad, 11 October, BBC One, 23:45 BST