testosterone, leading them to prefer louder, less subtle toys. Children generally know whether they are a boy or a girl around the age of two, but don’t grasp the fact that their gender is permanent at this age. The two-year mark also sees both sexes demonstrating

Surprise, surprise! There are gender differences in the way boys and girls tend to develop friendships from as early as three to four years. Generally, girls are better at empathising and have a stronger ability to read other children’s moods