That's perhaps your conclusion, but the reality is there do exist different generations with similar characteristics on a very general level. Of course social class, education, etc. are important as well.  
 Certainly no one is suggesting that everyone born between certain dates is exactly the same. And you're quite right, the start and end dates of any "generation" are somewhat grey. Also, as this is a somewhat esoteric topic, sources will be difficult to obtain; and of course their viewpoint will be as equally subjective as anyone's written above. Don't always look for someone else to back up your argument; state your case and then back it up yourself. Christopher Columbus did not rely on "sources".