Besides our formulas being a family tradition, it goes back to Greek Mythology and the story is below:
Apollo was also famous for being an oracular god, and had two cults in Delphi and Delos. People would come from all over the world to learn from Apollo what their future held. It was believed that, as the God of both medicine and plague, Apollo could heal people as well as cause disease by shooting people with his arrows.
Daphne was a Naiad Nymph in Greek Mythology, and was the daughter of a river god. She was famous for being incredibly beautiful and for catching the eye of Apollo. However, Daphne was determined to remain unmarried and untouched by a man by the rest of her life.
Greek Mythology states that Apollo had been mocking the God of Love, Eros (also known as Cupid). In retaliation, Eros fired two arrows: a gold arrow that struck Apollo and made him fall in love with Daphne, and a lead arrow that made Daphne hate Apollo. Under the spell of the arrow, Apollo continued to follow Daphne, but she continued to reject him. Apollo told Daphne that he would love her forever.
Daphne turned to the river god, Peneus, and pleaded for him to free her from Apollo. In response, Peneus use metamorphosis to turn Daphne into a laurel tree. Apollo used his powers of eternal youth and immortality to make Daphne’s laurel leaves evergreen. It’s believed that Daphne has to sacrifice her body and turn into a tree as this was the only way she could avoid Apollo’s sexual advances.
Resource:
 Apollo and Daphne: https://greekgodsandgoddesses.net – Greek Gods & Goddesses, November 30, 2016