This is because their DNA might be programmed to survive longer, as the genetic make-up in a man’s sperm changes as he gets older, favouring a far longer life.

The study, which appeared in the Proceedings of the National Academy of Sciences, points out that the chemical that protects chromosomes from damage, the telomere, shortens in most cells through life, preventing them from replicating.

However, new evidence shows that in sperm, the same chemical actually increases with age.

And, as the report says, "As paternal ancestors delay reproduction, longer telomere length will be passed to offspring, which could allow life span to be extended as populations survive to reproduce at older ages." This is despite the fact that delayed fatherhood increases the chances of miscarriage.

Not all doctors think the research is thorough enough though. Prof Thomas von Zglinicki, an expert in cellular ageing at Newcastle University said, "The authors did not examine health status in the first generation offspring.

"Very few of the studies that linked telomere length to health in late life have studied the impact, if any, of paternal age. It is still completely unclear whether telomere length at conception (or birth) or rate of telomere loss with age is more important for age-related morbidity and mortality risk in humans.”