Credit: Chris Jackson/Getty

Girl power!

If Duchess Kate and Prince William have a daughter someday, she can grow up to be Queen, even if she has younger brothers! 

Upending centuries of royal law, leaders of the 16 countries that recognize the British monarchy agreed Friday that a firstborn daughter should be able to ascend the throne even if she has younger brothers.

"The idea that a younger son should become monarch instead of an elder daughter simply because he's a man, or that a future monarch can marry someone of any faith except a Catholic -- this way of thinking is at odds with the modern countries that we’ve all become," British Prime Minister David Cameron said in a speech in Perth, Australia, at a conference of Commonwealth countries, as excerpted by the Los Angeles Times.

Cameron told reporters that "the time has come to change the rule so that if the royal couple have a girl rather than a boy, then that little girl will be our queen."

Although William and Kate, both 29, have only been married six months, they do have plans for kids in the fu true. "I think we'll take it one step in the time," William said in November. "We'll sort of get over the marriage thing first, then look at the kids. But obviously, we want a family."