Genetic and environmental contributions to saliva testosterone levels in male and female infant twins

Conclusions: Taken together, these data from the largest study of twin testosterone levels suggest that, in contrast to findings in adulthood, environmental factors determine the interindividual variability in testosterone levels in early infancy. This may have consequences for the development of sex-related behaviour during childhood and calls for studies designed to unravel specific genetic and environmental factors involved in this process. (Source: Psychoneuroendocrinology)

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