Who brought all of the misfortunes to the House of Atreus?

The misfortunes of the House of Atreus were brought upon by Tantalus, a King of Lydia, who was favored by the gods. However, for some reason, he loathed them. In an attempt to shock and trick the gods, he had his only son, Pelops, killed, cut into pieces, and boiled to be served to the gods.

The gods knew about this, however, and turned upon Tantalus, eternally punishing him by setting him in a pool of water, but when he was thirsty and reached down, the water would recede. He would also stand under a flourishing fruit tree, but whenever he was hungry and reached up, the wind would blow the branches away. Henceforth, he stood in a constant state of hunger and thirst. A curse seemed to hang over his descendants after that.

Pelops was restored to life, but since Demeter (or Thetis, the myths vary) already ate his shoulder, he was made a new one out of ivory. He was the only one of Tantalus' descendants who didn't have a life scarred with misfortune.