In a study of twins, University of Montreal researchers have found that testosterone levels are governed by environmental factors rather than inherited.
The study involved taking saliva samples from more than 300 pairs of both identical and non-identical twins and measuring testosterone levels. The researchers then compared testosterone levels between identical and fraternal twins to determine the contribution of genetic and environmental factors. The results indicated that differences in levels of testosterone were due mainly to environmental factors.
"Testosterone is a key hormone for the development of male reproductive organs, and it is also associated with behavioral traits, such as sexual behavior and aggression," said study author Dr. Richard E. Tremblay. "Our study is the largest to be undertaken with newborns, and our results contrast with the findings gained by scientists working with adolescents and adults, indicating that testosterone levels are inherited."
The findings, appearing in the journal Psychoneuroendocrinology, suggest that testosterone levels in infants are determined by the circumstances in which the child develops before and after birth. "Further studies will be needed to find out exactly what these influencing factors are and to what extent they change from birth to puberty," Tremblay concluded.
Discuss this article in our forum
Low testosterone cranks up risk for diabetes
Medicos explore antidepressant effect of testosterone
Obesity lowers testosterone levels
Source: University of Montreal