If a person in the old folks home is 70 years old in 2020, how old was that person in 1970? 20 years old. Too young to drink adult beverages. MJ was around back then.
In 1970, a 20 year olds parents could have been a pothead.
https://en.wikipedia.org/wiki/U.S._history_of_alcohol_minimum_purchase_age_by_state