Way back in first century A.D., Celtic Druids believed the mistletoe plant could recover fertility. This belief endured up to the Middle Ages, the 18th century, and until now. But then… when did the kissing custom become a “thing”? Supposedly some time in England, people’s servants were the first ones that started it. Then an early custom evolved where men were granted a stolen kiss from any woman standing beneath the mistletoe. If the lady refused, it was seen as bad luck.