in that people of an age group share a common culture that they grew up in that shifts over time and has aspects that are not common to earlier or younger generations.

That that environment may have an effect on the philosophy and ideals of the group as a whole isn't that absurd a notion.

This is the difference between that and astrology -- what's the difference between people born in early August and early July?  A month.

Generational studies are not astrology...maybe you ought to actually study this topic before making ridiculous statements like this.  Get a few books about generations and you'll see that there is an enormous amount of strong documentable science behind these different generational categories.

And if you get current books on generations, you'll see that Generation Jones is now getting equal treatment with the other generations.  No, it's not "call them tweeners or x'ers or zappers or whatever...", this group is called Generation Jones, and there are millions of people out there who are very glad that our long-lost generation finally has a name, and is being seen as a distinct cohort.