Plastic surgeon Dr Woffles Wu said premature white hair is a genetic predisposition, and can be handed down from one generation to another.

The 55-year-old doctor said: "With regard to Hong, she does not have a medical condition, and there is nothing wrong with it. It's genetic."

He added: "It's like if a father has a squarish jaw, his son will have a squarish jaw, and it does not mean that there is anything wrong. For example, I have a whole head of black hair at 55, and my grandfather had black hair till he was 75. Black hair is genetic as well."

He added: "Hair colour is a strange thing. In my years of medical practice, I've seen people with just a streak of white hair, or a whole tuft of white hair. It is very unusual, but it can be attractive as well. As it is genetic, it can occur as young as in your teens."