Some couples believe meeting "the one" is written in the stars.
But Lanarkshire couple Jim and Margaret Mitchell have more reason than most to believe in fate.
An accident after birth brought them together for the first time, before a chance meeting nearly two decades later reunited them for life.
This weekend they will toast 50 years of marriage and the series of coincidences that ensured they got together.
The mothers of Jim and Margaret Mitchell should have known something was different about their newborns from the start.
They were born at Lennox Castle Hospital in Lennoxtown on 15 and 17 September 1952 - when a maternity unit mix-up saw nurses briefly hand the babies to the wrong mothers.
Margaret, who turned 70 on Thursday, said: "Both our mums were called Margaret and the names caused confusion with the midwives so we were handed to each other's mums."
This happened in the days before name wristbands, but the mistake was realised within a few minutes by the babies' mothers and they were returned to their proper families.
Jim went off with his parents to live in Arden, south of Glasgow, and Margaret was taken home to to Knightswood, in the north-west of the city where they lived with family.
Soon after, Margaret's parents finally got their own house in Eastwood, Renfrewshire, only a 30 minute walk away from Jim.
By the time the pair reached 18, fate intervened again.
Retired engineer Jim said: "My friend was getting married and he had his reception back at his flat in Queen's Park in Glasgow.
"It was Margaret's friend Pat that married my friend David. That's when we met for the first time.
"We got chatting at the reception. I thought she looked fabulous in her lovely mini dress and so I summoned up the courage to ask her out.
"I was so pleased when she agreed because she was the best-looking girl in the room."
Within two months of seeing each other, the mums started to suspect that there was something familiar about the story.
Margaret said: "It was mainly Jim's mum. Because our birthdays were so close together and my name was Rafferty and my dad was the policeman, she just clicked after all those little things came together."
The two mothers eventually met for the first time since they swapped their babies back in the maternity ward and marvelled at the million-to-one romance.
Jim and Margaret were married in 1972 and now live in East Kilbride. They are retired and have two sons and a teenage granddaughter and grandson.
On Friday, the couple were celebrating their 50th wedding anniversary on the day in between their birthdays.
Margaret, a former sales executive, believes that if it wasn't for coincidence, she may never have chosen to go on a date with Jim.
"He was different to boys I was going out with. He had really long hair, but he was kind and thoughtful and totally different," she said.
Starting their day with breakfast in bed, they told BBC Radio's Good Morning Scotland programme about their secrets for a long happy marriage.
Margaret said: "It's just about getting on with each other and taking each day as it is."
Jim added: "You know, you have your ups and downs, but the best thing about falling out is falling in again."