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Older brothers affect chances of parenthood
20 November 2008
Having an older brother can cut the chances of you having children, according to new scientific research.
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A study conducted at Sheffield University found that male older siblings can have some kind of effect on their younger brother or sister's fertility.
The researchers looked at birth, death and marriage records over three generations of people in pre-industrial Finland.
It found that having an older brother meant there was a 62 per cent chance of having children, while 67 per cent of those with older sisters had children.
People who had older brothers were also found to have children at an older age than those who did not have them.
Published in the journal Evolution and Human Behaviour, the study authors said the findings were to do with nature rather than nurture and seemed to affect men and women equally.
They wrote: "The fact that men and women have a similarly reduced probability of reproducing when their elder sibling was male, suggests that the cost of being born after an elder brother may have consequences spread over a variety of physiological systems, affecting overall adult quality of both men and women."
Research out last month showed that wealthy men were more likely to have children than poorer men.
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