Important dig:

The British again! "As early as the 13th century, medieval monks in Britain were known to drink posset, a warm ale punch with eggs and figs. Over the years, this likely merged with the various milk and wine punches often served at social gatherings."

Social gatherings…as in cabal?

"When the brew was brought to the New World, colonists added their own twist. The rum that American colonists could get from the Caribbean was considerably less expensive than the other liquors shipped from England. And so, along with the readily available supply of milk and eggs in the colonies, the rum version quickly became a popular drink for people of all classes."

Why did they get to keep the sherry, while we colonists got stuck with the cheaper rum from the Caribbean? Did any of you anons know about this?

Dig eggnog anons. It's Christmas.

https://www.thespruceeats.com/origins-of-eggnog-760173