Pocket protectors. Says the London School of Economics:
London - Couples desperate to produce a son could boost their chances if one of them switches to a "masculine" profession such as engineering or accountancy, a report said on Sunday.
Equally, those keen for daughters are more likely to have success if they hold down "caring" jobs such as teaching or nursing, a British study has discovered.
The conclusion comes from a survey of 3 000 people from various professions by the London School of Economics and printed in the Journal of Theoretical Biology.
In the population as a whole in Britain, roughly 105 boys are currently born for every 100 girls, according to the study, The Sunday Times newspaper said.
But according to calculations by chief researcher Satoshi Kanazawa, for engineers and other "systemisers" the ratio is 140 boys per 100 girls.Nurses and the like produce around 135 girls for every 100 boys, the study found.
Kanazawa predicted that a physicist and a mathematician would be the most likely pairing to produce a boy, while a therapist and a chat show host would be odds-on favourites for a daughter.
The study did not say why this phenomenon occurred, but The Sunday Times quoted a specialist in evolutionary psychology as saying it could be because the children of "systemiser" parents appeared to encounter more testosterone in the womb, making their gender more likely to be male.