He now holds the Guinness World Record for the oldest sperm ever successfully used for in vitro fertilisation (IVF).
The father, a musician from Glasgow who holds the record anonymously, said he had a message for other cancer patients.
“People going through chemotherapy should keep hope,” he said.
“When we finally saw on a scan we were having twins I was in shock. I kept looking for a third heartbeat, thinking we might even be having triplets.”
He had his sperm frozen when he was diagnosed with cancer aged 21, and became a father to twins when he was 47. Doctors told him chemotherapy treatment would make him infertile so his sperm was frozen for 26 years and 243 days.
When he met his partner he had to explain that she would need IVF if they were to have children.
The couple, who live in Glasgow, did not use the sperm until 2010, when he was 47 and she was 37.
She became pregnant with twins and the boy and girl were born in 2011.
The father said he knew he held the record for the oldest sperm used in successful IVF but did not want publicity.
However, when he realised he could be listed anonymously by Guinness World Records he came forward and has now had his record accepted.
According to the Human Fertilisation and Embryology Authority the standard storage period for sperm is normally ten years, although in certain circumstances it can be kept for up to 55 years.
The father has now spoken out to highlight how long sperm can be frozen to create healthy children. The case raises the prospect of sperm being frozen with no time limit.
The man’s sperm was stored at an NHS lab in Edinburgh before his chemotherapy and, more than two decades later, used in the landmark treatment carried out at the GCRM fertility clinic in Glasgow by medical director Dr Marco Gaudoin.
Dr Gaudoin said: “Theoretically, it could be stored indefinitely.”
It is another world first for the fertility specialist who helped a same-sex couple become the first in Scotland to father twins by IVF. Last week it was revealed that cancer survivor Ryan Walker and his partner Chris Watson, from Falkirk, are expecting in the next few weeks, thanks to a surrogate mother who is also in a same-sex relationship.