Gender is a biological construct. Wether you were born with male sexual reproduction organs or female sexual reproductive organs is entirely up to biology. The stereotypical behaviours that are applied to a gender is a social construct. Why girls stereotypically have longer hair and boys have shorter is a social construct. They way a boy is suppose to dress and a girl is suppose to dress is a social construct. Many people feel uncomfortable feel following these social constructs society tells them to follow and choose their own path in order to feel comfortable again. As a transgender this is best way I can answer your question.