Okay, yes. Greek myth=confusing. And their family tree was tied in bewildering and creepy knots. But! As close as I can figure out:
Gaia, the Earth, was born of the Void.
Gaia bore Ouranos, the Sky, and Pontus, the Sea.
With Ouranos Gaia bore the Titans. With Pontus Gaia bore Ceto and Phorcys.
The Titans Chronos and Rhea were the parents of the Olympians. Ceto and Phorcys were the parents of, among others, the Gorgons.
Therefore, the gorgons are cousins/aunts/nieces to the Olympians, depending on which way you squint. And now my head hurts. Thank you.
- The Family Tree