haemophilia can usually be traced in the ancestry, in about 30% of cases there is no family history of the disorder, and the condition is speculated to be the result of spontaneous mutation in an ancestor. Victoria's appears to have been a spontaneous or de novo mutation, most likely inherited from one of her parents, and she is usually considered the source of the disease in modern cases of haemophilia among her descendants. Queen Victoria's father, Prince Edward, Duke of Kent, was not a haemophiliac, but the mutation may have arisen as a germline mutation within him. The rate of spontaneous mutation is known to increase with paternal age (and is higher in fathers than in mothers at all ages); Victoria's father was 51 at her birth. The probability of her mother having had a lover with haemophilia is minuscule given the low life expectancy of early 19th-century haemophiliacs. Her mother, Victoria, Duchess of Kent, was not known to have a family history of the disease, although it is possible that she was a carrier, but among her children only Victoria received the mutated copy. Queen Victoria's eldest daughter, Victoria, Princess Royal, apparently escaped the haemophilia gene, as it did not appear in any of her matrilineal descendants. Victoria's fifth child, Princess Helena, may or may not have been a carrier; two healthy sons survived to adulthood, but two other sons died in infancy, and her two daughters did not have issue. Victoria's sixth child, Princess Louise, died without issue. Queen Victoria's sons Edward VII, Alfred, Duke of Saxe-Coburg and Gotha, and Prince Arthur, Duke of Connaught and Strathearn were not haemophiliacs; however, her daughters Alice and Beatrice were confirmed carriers of the gene, and Victoria's son Leopold had haemophilia, making his daughter Princess Alice, Countess of Athlone a carrier as well. Queen Victoria family tree Children Victoria, German Empress (1840–1901) Issue: Wilhelm II of Germany, Charlotte, Duchess of Saxe-Meiningen, Prince Henry of Prussia, Prince Sigismund of Prussia, Viktoria, Princess Adolf of Schaumburg-Lippe, Prince Waldemar of Prussia, Sophia, Queen of the Hellenes, Margaret, Landgravine of Hesse-Kassel Edward VII, King of the United Kingdom (1841–1910) Issue: Prince Albert Victor, Duke of Clarence and Avondale, George V, Louise, Princess Royal, Princess Victoria, Maud, Queen of Norway, Prince Alexander John Princess Alice, Grand Duchess of Hesse and by Rhine (1843–1878) Issue: Victoria Mountbatten, Marchioness of Milford Haven, Grand Duchess Elizabeth Feodorovna of Russia,