Why did Hephaestus mother throw him off mount Olympus?

Hephaestus's mother, Hera, threw him off Mount Olympus because he was born deformed and considered unattractive. Displeased by his appearance and believing he was a disgrace, she cast him away in anger. This act ultimately led to his fall and subsequent life on earth, where he became the god of fire and craftsmanship.