A report from Sweden’s Karolinska Institute suggests that parenthood extends life expectancy by about two years. A man of my age (61) can expect to live 20 more years rather than the 18 allotted for the childless.

As is often the case, I find myself feeling grateful to my children. They have not only brought me pleasure, laughter and meaning but also it turns out that they are acting as a kind of elixir to keep me around. With four daughters – and I know this isn’t mathematically accurate, but allow me my fantasies – I reckon I should be good for at least another 25 years. The question is, why does this effect take place?

Nobody seems quite sure. Is it because people with children are happier? Not according to a Norwegian survey from 2012, which found that being childless made no difference to happiness. Or can it be down to avoidance of stress? Hardly. Children have brought me more stress than anyone in my life – almost as much as partners.

The researchers suggest it might be down to children helping to look after their ageing parents, be it through physical care, emotional support or arguing for better treatment. So maybe the difference is simply that, in a practical manner, your children watch out for your decaying husk as it gets ready to return to dust.

On imparting the fact of my daughters to new acquaintances, I have often been told that they will “look after me in my old age”. I’m not counting on it. My two eldest daughters have peremptorily remarked that they will bugger if they are going to spend any of their adulthood wiping my arse when I’m senile. I’ve always assumed – or hoped – that they are at least half joking, but maybe not. Values change. Perhaps we baby boomers are considered to have had enough good luck already.

But as I get older, I begin to wonder whether children have a responsibility to look after you in old age anyway. We hear a lot about the “sandwich generation” having to cope with infirm parents and growing children at the same time, so a lot of people clearly do feel that debt very strongly.

Surely, the argument runs, you gave your children life, shelter, encouragement, love and nourishment. Don’t they owe you something in return? In some cultures, it is a no-brainer that you owe your parents everything. But less so in the UK. My parents taught me that I owed them nothing, and I remain grateful for that, because I have seen the deployment of familial guilt as a weapon, and it is not something I want any part of. I never had the chance to look after either of them in their old age. I would have done – but not out of guilt.

Anyway, I’m afraid the children have an unanswerable counter-argument to claims of responsibility, even though it pains me to concede it. This is, “Well, you chose to have me – I didn’t ask to be born.” Banal though that may be, it feels true. So it is your responsibility to look after them. But it is not their responsibility to look after you.

If my children are going to have a part in looking after me in my dotage, it has to be a choice born of love, not duty – because that will make the child resent, even hate, me and I don’t want that to be my last experience of my children on this earth.

I would never want to be looked after by someone who begrudged the fact. I would rather be in a care home – or on the street. If the support doesn’t come from the heart rather than some anguished moral balance sheet, then I’m not interested. Although, I may feel differently when I’m 90 and can’t even change my own adult nappies. In other words, I may live to regret this column. But then again, with any luck, I won’t remember writing it in the first place.