MEN’S testosterone levels are largely determined by their environment during childhood, according to new research.

The Durham University-led study suggests that men who grow up in more challenging conditions where there are lots of infectious diseases, for example, are likely to have lower testosterone levels in later life than those who spend their childhood in healthier environments.

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

The researchers say the differences are linked to energy investment as it may only be possible to have high testosterone levels if there are not many other demands placed on the body such as fighting off infections.?

Lead author Dr Kesson Magid, from Durham’s anthropology department, 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.”

As high testosterone potentially lead to increased risk of prostate enlargement and cancer, the researchers say screening for risk may need to take account of a man’s childhood environment.

Co-author professor Gillian Bentley added: “Very high and very low testosterone levels can have implications for men’s health and it could be important to know more about men’s childhood circumstances to build a fuller picture of their risk factors for certain conditions or diseases.”