Tales of brothers feuding, often ending with one committing fratricide, are unsettlingly common in mythology. Set murdered Osiris, Romulus killed Remus, and Oedipus’s sons Eteocles and Polynices killed each other. More recently, and less imaginatively, Adolf and Rudolf Dassler (of Adidas and Puma fame respectively) and Sterling and Stephen Clark (heirs to the Singer sewing machine fortune) turned their backs on one another, over money.