 His father was the second son of King George I of Greece and his mother the only daughter of the French botanist Prince Roland Bonaparte and Marie-Félix Blanc.Peter was born in Paris and spent his childhood in France, and did not set foot in Greece between 1912 and 1935 due to the First World War and the later proclamation of the Second Hellenic Republic.During that time, he came to know Denmark, the kingdom from which the Greek royal family originated.