to influence manifestations of neurodevelopmental disorders through effects on the intrauterine environment. For example, Eriksson and colleagues 34 investigated whether elevated levels of testosterone in utero increase the risk of developing ASD or ADHD traits, by assuming fetuses with a male co‐twin will be exposed to higher levels of endogenous testosterone than fetuses with a female co‐twin, leading to greater masculinization of the brain. Their data did not support this hypothesis, and instead they reported that presence of a female co‐twin corresponded to a greater risk for ASD or ADHD traits. 34 Recent advances in neuroscience suggest that the female brain may exhibit greater plasticity in response to challenges. 35 This would be expected to lead to lower prevalence of cognitive dysfunction or other disorders, such as ASD, which may be influenced by such environmental exposures. In fact, one study demonstrated testosterone levels in boys mediated prefrontal‐hippocampal covariance, but this was not shown in girls. 36
