"Twin Study: Female Twins with Male Siblings Show 'Manly' Behaviors Due to Womb Testosterone Transfer"

Female twins with a male sibling may exhibit traditionally male behaviors due to exposure to testosterone in the womb, which can impact their behavior, personality, and life outcomes. While some studies suggest negative effects such as decreased fertility and educational attainment, other researchers are less convinced of this pattern and attribute the complexity of the issue to environmental factors like exposure to chemicals.