In marrying Euphrosyne, who was his aunt and eleven years his junior, Carathéodory was following a family tradition of marrying close relatives.
Sa marrying Euphrosyne, na kanyang tiyahin at labing-isa taon ng kanyang junior, Carathéodory ay sumusunod na ang isang pamilya na tradisyon ng marrying malapit na kamag-anak.