A parenting expert believes Prince Harry’s recent behaviour can be easily explained by his birth order.

Author of Why First-Borns Rule the World and Last-Borns Want to Change it, Michael Grose, said the Duke of Sussex has a case of second child syndrome.

“William is the heir and Harry is the spare, so in some ways all of this carry on … you can look at from the birth order behavior,” he said.

“He shares those characteristics of a second, which is a little bit more rebellious, and a lot of the charmer and extra version of the younger one.”

He said most personalities can be clearly defined by birth order.

“The first one is what we call the family conservative, if it’s an academic family, it’s a fair chance the first born will go down an academic path,” he said.

“They value authority a bit more, and parent resources go on their shoulders.

“The second one is really about divergence and difference.

“Often the middle one is more likely to leave the family first, they are a little bit more adaptable, and they score really well on resilience surveys.”

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(Photo: Kevin Mazur/ Getty Images.)