Childhood environment major factor in determining testosterone levels – study

A man’s testosterone levels are more likely to be determined by his environment during childhood than by any other factor, new research has suggested.

Scientists at Durham University said males who grow up in more challenging conditions where there is an abundance of infectious disease or poverty should expect to have lower levels of the hormone – commonly associated with aggression – than those who spend their childhoods in healthier environments.

The study, published in the Nature Ecology and Evolution journal, challenges the theory that testosterone levels are controlled by genetics or race, researchers said.

The study involved data collected from 359 men on height, weight, age of puberty and other health information along with saliva samples to examine their testosterone levels.

Researchers then compared the following groups – men born and still resident in Bangladesh, Bangladeshi men who moved to the UK as children, Bangladeshi men who moved to the UK as adults, second-generation UK-born men whose parents were Bangladeshi migrants, and UK-born ethnic Europeans.

The study found that Bangladeshi men who grew up and lived as adults in the UK had significantly higher levels of testosterone compared with relatively well-off men who grew up and lived in Bangladesh as adults.

Bangladeshis in Britain also reached puberty at a younger age and were taller than men who lived in Bangladesh throughout their childhood, the study suggested.

Dr Kesson Magid, lead author of the study, said men with higher levels of testosterone are at greater risk of potentially adverse effects of the hormone on health and ageing, while very low testosterone levels in men can include lack of energy, loss of libido and erectile dysfunction.

He said: “A man’s absolute levels of testosterone are unlikely to relate to their ethnicity or where they live as adults but instead reflect their surroundings when they were children.”