Andy Hallsworth (57) was told the momentous news on Long Lost Family: Born Without Trace when he also learned he was the eldest of eight children.
Andy, who was born “on or about 31 August 1965” was abandoned six weeks later by his Irish Catholic parents who feared being outcasts in their very religious families after his mum became pregnant before their wedding.
After he was discovered and later adopted, Andy led a happy childhood, oblivious to the fact he had been abandoned.
It was only later, when he was questioned about his medical history before the birth of his first of two children, that he was told he was a foundling.
Zookeeper Andy, of Norfolk, asked Long Lost Family for help in finding his biological parents, and eventually, thanks to DNA testing, they found that his mother was still alive in Ireland and wanted to meet him.
He also found out he was the eldest of eight children although his father sadly died in 2009, having always remained married to his mother, who wanted to remain unidentified.
When he is shown a photograph of his parents, that didn't show their faces, Andy exclaims: “He really does look like me. Look at his eyes.”
“I never thought in my wildest dreams that I would ever see this."
When told his mother who is now 82 would like to meet him, an emotional Andy nods and says quietly "That's brilliant news.”
Andy then travelled to Ireland to meet her and also visited his birth father's grave.
As his mother didn't wish to be identified, their reunion was filmed away from the cameras.
But following the meeting, Andy said: “When I came to the door we looked in each other’s eyes and had a little hug and then we've been talking for the last three hours so it's been great, really nice.
“She said it was a terrible feeling what she had done and what she had to do but there was no way she could've come back here with a baby, she would've been banished and outcast, which I completely understand.
“But they had thought about me all through their lives and quietly wondered what had happened and that's really good to know. It was so nice to tell her I had a happy childhood.
“I know why I am the way I am, I've met my mum and I know where I'm from which I didn't know. I couldn't have wished for anything better.”
During the show he also visited the church where he was abandoned, St Mary of the Angels in Bayswater.
Returning to the place where he was abandoned for the first time, Andy said: "That's the church then I guess. All I know was my name was David Sutherland, that I was found in Sutherland Place near or on the steps of a church.
“This is where I got my surname. It's so strange to think that this is where possibly my mum must have left me.”