Marcus and Helen are discussing their children's understanding of gender.

• Marcus: "Our 3-year-old son, Leo, thinks he will grow up to be a daddy, but yesterday he saw his uncle wearing a kilt and insisted his uncle had turned into a lady."
• Helen: "Our 7-year-old daughter, Chloe, knows she is a girl and is now obsessed with watching female tennis players and copying how they dress and play."

Discuss cognitive explanations of gender development. Refer to the comments of Marcus and Helen in your answer.