Along with love, death and heartbreak, the concept of age has spawned countless well-known sayings.

"Age is just a number", "act your age, not your shoe size", and, "a man is only as old as the woman he feels"(we assume this also applies vice versa).

Age gaps in relationships are fascinating to many of us. Whether we're mystified, horrified or in the "good on you!" camp, a dramatic difference in age piques our interest.

Because according to a recent study , there IS a correlation between relationship age gaps and the longevity of said relationship.

So is it just number? Or is it a case of "mind the gap"?

The study by Andrew Frances and Hugo Mialon from Emory University, Atlanta surveyed 3000 married participants.

Their findings showed the larger the age gap, the greater the chance the relationship will end, and this likelihood goes up incrementally.

So a gap of five years age gap means a couple are 18 per cent more likely to break up than age equals. This goes up to 39 per cent with a 10 year age gap, and 95 per cent with a 20 year gap.

And the most successful age gap?

Apparently no more than a year, for which there's only a three per cent chance of going your separate ways.

Of course, it's rare there's only one reason behind two people's decision to call time on their relationship, and Mialon did admit to the Indy100 :

"It could just be that the types of couples with those characteristics are the types of couples who are, on average, more likely to divorce for other reasons."