Even conceptualizing, not to mention also describing, generalizing about and "explaining" Millennials, is a tricky and risky undertaking. Despite the deceptive homogeneity suggested by the single label, "Millennial", the fact is that the youngest and the oldest Millennials are, as most commonly defined, separated by a full generation-20 years, while nonetheless presumably defining one.
But how easy is it to imagine that the tough-times depression-era generation reaching adulthood just before Hitler invaded Poland in 1939 would have been virtually indistinguishable from, felt any broad kinship with, or have really been comprehensible to the well-wheeled, free-wheeling suede-shoes generation reaching adulthood in 1959-on the eve of the even more free-spirited Hippie revolution?
Moreover, the two decades spanning 1980 to 2000, generally regarded (and in this report also accepted) as defining "Millennial", have at least two dramatic and definitive historical divides: the partitions into pre- and post-911 mentalities and into pre- and post-social media mindedness.
This makes the likelihood that now, in 2015, 15-year-old and 35-year-old "Millennials" have essentially the same personalities and character as minuscule as the chance that "peace and love" would mean the same thing to a San Francisco 60's LSD-tripping flower child and an unforgetting, perhaps unforgiving survivor of the attack on Pearl Harbor. This should be obvious without even factoring in the fact that a large percentage of Millennials are adolescents and the rest are not (being at least nominally adults).