It all began with a harmless game of soccer among young men in northwestern Albania. After one of the players had been injured in a subsequent dispute, his team members shot a relative of the suspected attacker. Now the male members of the families involved in the blood feud do not dare leave their homes. Such vendettas and blood feuds occur in many societies, sometimes lasting for decades. The harm for the participants is enormous and lacks apparent benefit, as the participants often no longer remember what actually triggered the quarrel. Theoretical calculations also demonstrate that vendettas are costly for the participants from an evolutionary point of view and should therefore not develop. Scientists have now investigated the genesis of vendettas.