Zeus was born to the brother and sister duo (yup) of Titans Kronos and Rhea. Like his father, Uranus, Kronos had heard a prophecy that one of his sons would dethrone him. Rather than take a risk of being bested, Kronos did what any logical father would do every time his wife gave birth: He took the newborn and swallowed it whole. Yikes.
Thanks to that unsettling strategy, the couple's first kids, Hera, Poseidon, Hades, Hestia, and Demeter all spent their first years in the belly of Kronos. Rhea (unsurprisingly) wasn't super-stoked about the situation, so when she gave birth to their sixth child, Zeus, she smuggled him to Crete and swapped in a blanket-wrapped stone to fool Kronos. Kronos swallowed the stone and Zeus went on to be raised by nymphs on the island of Crete. Eventually, Zeus and Rhea got Kronos to vomit up the other kids (and the stone!), and Zeus led his siblings in a revolt to overthrow Kronos and the Titans. When they won, Zeus, Hades, and Poseidon divvied up the world amongst themselves: The underworld went to Hades, Poseidon scored the seas and oceans, and Zeus got the skies, putting him above all other gods — literally.