I guess my question would be "how can we, in the aggregate,
not be the same?" You start with people. Divide them up however you want. Why would being a zygote that pops out in one year as opposed to twenty years before of after possibly be any different on an aggregate level?
The thing that makes a generation "brave" is being raised with enemies encircling you. "Frugal" is a depression and watching your parents stretch every penny. "Tough" is get in the crop or die. "Adventurous" and "open minded" probably come from feeling safe enough to experiment and being exposed to enough of a variation of people not to be bigoted.
But
none of those things are virtues of the people themselves. They're the lab conditions that one sample was grown under rather than another. Those characteristics aren't chosen. If there's any choices involved they are actually those of each generation's parenting choices -- one might say the Boomers' parents raised spendthrift irresponsible tax evaders. If anything that means the Boomers raised the generations who are critical of them now, so if those younger generations feel in any way noble or superior or more evolved, that's actually to the credit of their parents, not them.
I don't have a dog in this fight -- I'm an Xer raised by Greatests. The Boomers have no personal presence in my life, so possibly I can be a little more objective about them.