Men’s fertility clocks tick, too

Over the past decade men and women have been having children later in life, with worries about money and career prospects among the main reasons for the delay. But it may surprise you to learn that the average age of conception has stayed consistent over the past few thousand years, reports the journal Science Advances. Down the centuries, the average age a man has children has been 31, a woman, 23.

The scientists’ calculations were based on comparing the DNA of modern humans with DNA from the remains of our more distant ancestors. But all else being equal, is there an ideal age to start procreating?

Most women are only too aware that at 30 their fertility starts to decline.

Yet men have nothing to be complacent about: one study found that, even with a much younger partner, men over 40 are 30 per cent less likely to conceive than men under 30. And their children are more likely to develop autism and bipolar disorder. Something I may drop into conversation the next time I see my sons.