The Queen' s oldest granddaughter, Zara Tindall, isn't a princess due to a royal tradition - even though both Beatrice and Eugenie are princesses. Zara's cousins, Prince William and Prince Harry, both hold the royal rank, but her brother, Peter Phillips, doesn't - and it's all down to their parents.
Royal Family tradition dictates that only the father passes on his official title, so the children of Prince Andrew, Prince Charles, and Prince Edward all automatically became princes or princesses. However, because Peter and Zara are the children of Princess Anne they didn't receive the HRH status.
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Zara Tindall and Peter Phillips are the only children of Princess Anne and her ex-husband, Mark Phillips. Mark isn't a member of the royal family, else they would have inherited his title.
However, it has been reported that Princess Anne didn't want her children to have official titles, according to former Buckingham Palace press secretary Dickie Arbiter
He said: "It was a masterstroke of the Princess Royal when she decided not to give her children titles.
"Growing up as a commoner allowed Zara to thrive as her own woman, and there has never been pressure on her to conform. She has benefited from it in all sorts of ways."
Away from the public eye, Zara has built herself a successful life as an equestrian, and even won a silver medal at the London 2012 Olympic games.
She has three children with her husband, Mike Tindall, and recently welcomed baby Lucas Philip into their family, who joins Mia Grace and Lena Elizabeth.
Meanwhile, we earlier reported how Princess Anne, the Queen 's only daughter, is 16th in line to the throne - behind Prince Andrew and Prince Harry - despite being the late Monarch's second oldest child.
'Primogeniture' determines how children inherit their parents' estate, and rules that apply to the rest of us also apply to the Royal Family and affect their chances of becoming King or Queen.
But due to a law enacted in 1701, the Royal Family operates under 'male-preference primogeniture', where male children receive a more prominent position than females.
The Queen overturned the rule in 2013 under the Succession to the Crown Act, which gave women equal rights, but it wasn't backdated so Princess Anne's position remained unchanged.
Since the 2013 change, succession now goes to the next member of the Royal Family in birth order, applying to anyone who was born after 2011.
This means that Princess Charlotte, the daughter of the Duke and Duchess of Cambridge, will be the first female heir who is not displaced by her younger brother, Prince Louis.
The Royal family's website has a full list of succession, but ahead of Princess Anne are Prince Charles, Prince William, Prince George, Princess Charlotte, Prince Louis, Prince Harry, Prince Andrew and Princess Beatrice, among others.
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