I collect antique postcards from roughly before 1950, with a specific focus on cards depicting airships, zeppelins, and related topics. It’s fun and I get pretty serious about organizing and cataloging them and storing them in a safe archival fashion (at least as well as I can at-home). I also have a few smaller topic areas that I collect cards from.
In the literal sense, yes, but not in the context of marketing cohorts, which are usually based on birth date ranges and are used to group members of society who experience similar pressures and exhibit similar behaviors. Gen Y/Millennial and Gen Z are marketing terms, so it’s possible for a parent to have a child in each.