Also...Gen X is from 1965 to 1976, and Gen Y from 1977 to 1994...where did you get those dates?
Your dates are from the PersonalityCafe is'nt it? The mine are from wikipedia, and it's supposed to be the original classifications, from the originals classificators:
http://en.wikipedia.org/wiki/Generations_(book). It makes more sense for me. My parents for examples are born in the early 60s and they don't consider them as Baby Boomer, and I also considerate peoples born in the late 70s as X, not Y, teenagers born in the late 90s are Y, but yes, probably the very last Y.
I can't get behind SJ for all of these turn of the century generations, because the 1920's were a time of EXTREME rebellion compared to the Victorian Era that makes the 1960's look like a tea party in comparison...what that generation did in the 1920's was completely off the wall in contrast to their parents' generation, and even in the 1930's there was a subversiveness to literature and film that was later repressed in the more unified WWII 40's and McCarthyite conservative 50's.
The Lost Generation, wich means peoples born in the late 19 th century who matured in the early 20th century, is the generation where every WWI veterans are born. My impressions is that generation is a combination of right-doers conservative warriors (ISTJ) and more rebellious and revengeful warriors (ISTP), but apparently I underestimate that rebelious side, I would be curious to know more about that period.

I agree that 60s were a tea party in comparaison and this is why I've type the BOOM generation as 7ish ISFP/ENFP, nice and laid-back hippies who are militant, innovative, creative, driven by values and optimistic about the future possibilities. Also, you said that 40's and 50's were a period of repression and unification, wich confirm the high STJ leanings of the Lost Generation and G.I Generation for me.
It's also impossible to type Gen Z because they're too young.
Yes, but some sociologist have etablished some characteristics about them. It's just an impression of how they are and/or are likely to became. The Generation Z is named the New Silent Genearation, a behind-the-scene generation who is less assertive and ambitious than the precedent generation, and more reposed in family and the close social circle. It's also a Digital Natives generation where peoples have a merging relationships with technology and more reposed on technology than communication. Sounds like an ISFJ/INTP combo for me.