Younger children who bend the truth have a cognitive advantage over the ones who don't. "Lying requires two ingredients," researcher explained. "Children need to understand what's in someone else's mind—to know what they know and what they don't know. We call this ability theory of mind. The children who are better at theory of mind are also better at lying."

Researchers have found that the ability to tell fibs at the age of two is a sign of a fast developing brain and means they are more likely to have successful lives.They found that the more plausible the lie, the more quick witted they will be in later years and the better their abiliy to think on their feet.

It also means that they have developed "executive function" - the ability to invent a convincing lie by keeping the truth at the back of their mind.

“Parents should not be alarmed if their child tells a fib,” said Dr Kang Lee, director of the Institute of Child Study at Toronto University who carried out the research.“Almost all children lie. Those who have better cognitive development lie better because they can cover up their tracks. They may make bankers in later life.”