Honestly, I think it's a combination of culture...I grew up watching 80s tv shows and movies, does that make me an 80's kid? Hell no, I was born in 1986 for crying out loud, only have 1 memory of Christmas, '89 and that's it...
Think about what you remember from the decade, not just television and movies because syndication really doesn't count...if you remember probably 85% of these than you're probably a 90s kid (I mean actually remember, not being told about it...)
*the Oklahoma City Bombing (my teacher told us after recess, we almost got sent home)
*OJ Simpson (we watched it during school)
*Clinton being elected twice
*Clinton's "I did not have sexual relations..."
*Columbine (I was already in jr. high when that happened)
*Princess Diana dying
*Chicago Bulls being everyone's favorite team
*When Dolly was the first cloned sheep (I did a current event assignment on it)