I was born in '81 so I am right at the border of X and Y.
Do you know the movie Garden State? I once had a discussion with my friends that if you can genuinely relate to the characters in this movie and the struggles they are going through you are probably part of Gen Y, if not you are probably part of Gen X. It's my favourite movie so I guess that makes me a Yer.
I showed it to people who were my age or just a few years younger and they completely related to it while most people older than me or more than 7 or 8 years younger than me tend not to get the movie and find it boring.
And concerning the whole discussion about the collapse of the Soviet Union, I was born in East Germany behind the Iron Curtain and 8 when the Berlin Wall collapsed and I don't remember much about it, it certainly didn't influence my thinking massively because I just didn't have the mental framework to realise what was happening (while for example the war in Yugoslavia a few years later was something that definitely struck a cord with me) However my mum who was 30 when Communism collapsed has been marked by the change, she once told me she would never believe in something as strongly again as she did in Socialism, since the collapse of a whole system and everything she was brought up to believe in was just far too much of a traumatic experience for her.