Mistletoe confusion

Mistletoes are from a poisonous and parasitic shrub. Why would we hang it above our heads and try to find someone to kiss beneath it in the season of love and happiness??? Does that make sense? An old german mythology even tells that a mistletoe was responsible for some giants death while hanging above him! But I guess since it became the magic ingredient of Asterix' and Obelix'  magic drink there must be something good about it. For all you men out there.... go for it!! :)