What are the estimated year gaps to be considered a “80s baby"? ( Or 90s,00s,40s,70s,etc.)

In other words, what year of birth would “officially” make someone a “70s kid,” “10s kid”, etc?
 
I’m not sure whether the estimated year ranges would be based on decades or how much of the period you can recall from childhood. In one case, for example, would being born between the years 1990–1999 automatically make someone a “90s baby”? As opposed to being born between, let say, 1986–1993? In another case, a person born in the year 1960 could probably be a 60s kid, much like how a person born in the year 2010 could be a 10s kids.
 
I have two older siblings that were born in 1984 and 1986. Would my oldest sibling be a 80s kid while my other sibling would fall somewhere in between being a 80s or 90s kid? I also have a younger cousin who was born in 1999. In my cousin’s case, would it be safe to assume that she is more of a 00s kid than a 90s kid?