He isn't Really My Brother

Monica was the only little girl on her street, but when she was eight years old, another girl came to live in the house opposite hers.
The new girl was eight years old too,and her name was Joana.
Joana had two brothers. She didn't go to the same school as Monica, but they soon began to play together after school.

One day Joana came home, had her miLk and cookies, and then went to Monica's house. She said to her friend, "Hi,Monica. Will you come to my house to play ? I've got a nice new game!"

Monica answered,"I'm sorry Joana, but my mother won't let me play with you today, because your brother,George has a bad cold, and she doesn't want me to get it,too."

"Oh,that's all right,Monica," Joana answered quickly. "George isn't really my brother.He's my step-brother."

Can you find the funny thing from the story ?Leave your comment :)