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Newly christened George of Cambridge joins Prince Christian of Denmark, Prince Moulay Hassan of Morocco and Prince Hisahito of Japan as the world's youngest male heirs.
Some had hoped that William and Kate's child would be a girl, as it would be the first time a British heir's eldest child would inherit the throne regardless of its gender, but given that there are five young female heirs across Europe, Prince George is actually in the minority as a boy.
In Denmark seven-year-old Prince Christian stands second in line to the throne after his father, Prince Frederik, and in Japan Prince Hisahito of Akishino is heir to the Chrysanthemum throne.
Prince Moulay Hassan of Morocco is the world's fourth young male heir. Prince Moulay Hassan, who celebrated his 10th birthday in May, is the son of King Mohammed I and Princess Lalla Salma of Morocco.
The quartet, however, are outnumbered by Europe's young future queens as Norway, Belgium, Sweden, Spain and the Netherlands all have female heirs.
Princess Elisabeth of Belgium, 11, Princess Amalia of the Netherlands, nine, Princess Ingrid of Norway, nine, and seven-year-old Princess Leonor of Spain all share the same royal destiny; as does Princess Estelle of Sweden, one, who is the youngest of the group and will be closest in age to Prince George.