By Fred Gardner

Why does the presence of mistletoe —a parasitic plant that roots in oaks and other host trees— confer the right to kiss whoever you’re with?

The answer occurred to John Lee, MD, a family practitioner in Mill Valley, back in 1967. Lee was then editing the Marin Medical Society Bulletin and on the lookout for topics for his monthly column. He came across an article in a Harvard alumni publication describing the pagan rituals of the Celts  who lived in the British Isles in the millennium before Christ. For their winter solstice celebration, the Celtic priests —Druids— would collect berries from trees bearing mistletoe.

Coincidentally, Lee had just read an item in the Journal of the American Medical Association stating that mistletoe contains a compound very similar to progesterone. He had an insight: “The berries were life in the middle of that cold European winter, when everything else was bleak and apparently lifeless. The Druids called mistletoe ‘a gift from the gods.’ They would take these berries and mix them with hot mead [an alcohol drink made from fermented honey] and they would all have a weeklong party where gifts were exchanged and they would celebrate that the sun was going to return and winter would not mean the end of the world.

“When a woman takes progesterone and then quits, a period is induced. I realized the mead laced with mistletoe would decrease everyone’s inhibitions and increase everyone’s libido for their four- or five-day party. It was free sex! And after four or five days of celebration they would quit. All the women would have their periods, and no babies would occur. No wonder they called it ‘a gift from the Gods!”  

Lee compares the discovery that mistletoe prevented pregnancy to the discovery that limes prevented scurvy —a major advance in the annals of medicine.  “The sailors didn’t know it was Vitamin C.  The Celts didn’t know it was progesterone. They just knew it worked.”  Lee hypothesized that kissing under the mistletoe is a form of “symbolic sexual promiscuity” going back to the days when the berries served as a birth-control device during pagan winter solstice parties (the persecuted Christians having scheduled their own holidays to coincide with existing celebrations).

Lee’s editorial evoked no response from the readers of the Marin Medical Society Bulletin —maybe they were disturbed by the juxtaposition of Christmas and sex— and never made it into the general lore. But have you ever heard a more plausible explanation of the tradition?

A gift from the Gods, indeed. Merry Christmas, everybody.