It’s not every day that someone sets a Guinness World Record, especially when they’re only 6 months old. But that’s what happened when baby Xavier Powell was born using the world’s oldest human sperm.

Baby Xavier’s story starts when his dad, Australian Alex Powell, was 15 years old. He was diagnosed with Hodgkin’s lymphoma, a cancer of the lymphatic system in which cells grow abnormally and hinder a person’s ability to fight off infections, The Inquisitr reported. Though it’s not entirely clear what causes the disease, chemotherapy, radiation, or stem cell treatment have been found to put it into remission. So when doctors told Powell he’d be undergoing chemotherapy to fight the disease, his mother, who’d had a conversation with a stranger about storing sperm that same day, suggested he do the same.

One of the side effects of chemotherapy is infertility. While not every man who undergoes chemotherapy will be made infertile, it can affect how much sperm a man produces and the sperm’s ability to fertilize an egg. Though he may not have known it at the time, his frozen sperm would eventually become very useful.

That’s because in 2013, when Powell and his wife Vi decided to have a baby, they found that, although the Hodgkin’s lymphoma was gone, Powell was indeed infertile. The couple decided to try in-vitro fertilization (IVF), “a complex series of procedures used to treat fertility or genetic problems and assist with the conception of a child,” according to the Mayo Clinic. Therefore, the only viable route they had to conceiving a biological baby was to use Powell’s 23-year-old sperm.

This 23-year gap is what set the world record — Powell’s sperm is the oldest human sperm in the world. And despite skepticism, a year after they started IVF, they were successful. Xavier was born on June 17, 2015. “For me, it’s that sort of feeling in life you want to relive every moment if you can,” Alex told Australian news service 9News, when asked about the birth of his healthy son.

Normally, sperm can be stored frozen for up to 10 years. However, for people who are fertile, there’s a chance it can be stored for a maximum of 55 years. For people who no longer need the sperm, it’s typically donated or used in research. After experiencing the hardships of using two-decades-old sperm, the Powells are ready for another child — so they will use IVF again.

If you’re wondering, the previous record holder for baby born from the world’s oldest sperm was surpassed by Xavier by only a year.