"Tévez has a distinctive burn mark from his right ear, down his neck to his chest. This occurred when he was ten months old while he was exploring his mother’s kitchen floor and he inadvertently pulled a kettle of boiling water over himself. This caused third-degree burns to the right side of his face, neck and chest and left him in intensive care for almost two months. Today, the scars are a highly visible feature of Tévez, who did not get them fixed because he was playing in a junior football team. He refused an offer from his then club, Boca Juniors, to have them cosmetically improved, saying that the scars were a part of who he was in the past and who he is today."
Every official source, tv program,book and interviews with Tevez himself says a form of the above, either he was having fun with you or you are lying.The fact it looks nothing like a knife cut and everything like a burn makes me believe the latter.