Why did Michael Jackson have curly hair?

In 1984, during a commercial Michael was shooting for Pepsi, he was on stage performing when a fireworks display, used for special effects, fired off from behind him at the wrong timing. It was so close that it reached his hair, and it caught on fire. He suffered second and third degree burns on his scalp. Later on, he started to wear wigs because some of his hair couldn't grow back.