I've read many threads that people born in 1986 are completely different from those born in 1985 just because the former cohort started high school in 2000 while the latter cohort entered in 1999. First of all, I was born and raised in Florida (West Palm Beach to be exact) where the cutoff date is September 1 (not December 31), meaning it was based off near the school year and NOT THE FREAKING CALENDAR YEAR!!!!!!!!! Second off, I missed the cutoff because I was born on September 27, 1986, and therefore, I couldn't start kindergarten until 1992, which means I started high school in 2001 (much like all my 1986-born friends/classmates with September 2-December 31 birthdays) and NOT 2000. I had a few friends born between September 2-December 31, 1985 that all started high school in the year 2000, so with that logic, you can't call them Xillennials either nor can you say they have any more Gen X traits than I do because none of us have any Gen X traits. When I moved to Georgia briefly in 1994 during the early part of second grade and then again in 2004 (this time, for good) for my senior year, all of my classmates (minus the ones that were held back) were the exact same age (September 2, 1986-September 1, 1987) because Georgia has a similar cutoff to Florida. Yes, my cohort (late 1986) spent all of their years in high school during the 2000s but so did the late 1985 cohort. I know there are a couple of states like New York that have calendar year cutoffs but guess what, not everyone lives in freaking New York.
There's another reason Redditors love to separate 1986-borns from 1985-borns: 1985-borns were the last to remember the 80s just because they turned 4 in 1989 while 1986-borns could only remember up to 1990 when they turned 4. First off, how is being 4 any more significant than being 3? Both ages are within the post-toddler phase, people can remember being 3 just as well as being 4. As a September 1986-born, I remember living with my mom and grandmother during the summer of 1989 before I was even 3, and I remember the exact house my mom moved in a month after me and my twin brother turned 3. I also remember seeing The Little Mermaid (that's right, the Disney film, not the live-action 1990 film with Cher and Winona Ryder) in theaters in November 1989, and I remember my older cousins having stuff like Teddy Ruxpin, the board game Mouse Trap, and NES games like Super Mario, Duck Hunt, Kung Fu, and Mike Tyson's Punch Out. I remember when The Simpsons debuted on Fox channel 29. I even remember hearing Babyface's "Tender Lover" on the radio during that time. Do I have a full year of memory during the 80s like a 1985-born? Absolutely not because while I remember the earlier parts of 1989 when I was seeing brick house and balloons flying to the sky, they were very fuzzy and I didn't even realize those brick houses were actually part of the University of Florida in Gainesville until three and a half years later but that don't mean I have zero memories of 1989. Am I a 90s kid? Absolutely but I'm also a 90s kid that remembers THE ENTIRE DECADE (Including January-September, not just from October 1990 onwards).
I've also read that 1986-borns grew up with 1991 and 1992-borns just because they all started high school during the 2000s, which is stupid because there's a 5-to-6-year gap between my cohort and those born in 1991-1992. I wasn't a preteen at any point during the 2000s because I became a teenager in late 1999, started high school a month before 9/11, was among the youngest voters of the 2004 election, and graduated in May 2005 (which is after YouTube's launch but YouTube didn't even get any notice from the public until around November). 1991 and 1992-borns spent the early part of the 2000s as preteens and didn’t even become teenagers until 2004-2005 and their high school years were shaped by a mainstream YouTube, an available-to-everyone Facebook, and a rising Twitter. January-September 1, 1991-borns didn't even begin high school until August 2005 (which was three months after I graduated), September 2, 1991-September 1, 1992-borns started high school a year later (August 2006), while September 2-December 31, 1992-borns started even later (August 2007), and that means I didn't go to high school with them at any point in history.
Another thing that separates me from 1991 and 1992-borns is that I grew up with Teenage Mutant Ninja Turtles, DuckTales, and Chip N' Dale, and remember the debuts of Darkwing Duck, X-Men and Mighty Morphin' Power Rangers. I remember freaking James Bond Jr., something 1991 and 1992-borns never even had a clue about until they looked it up online. The early part of my adolescent years was during the Y2K era when Nu-Metal, late 90s pop rap, teenyboppers, Pokémon, Trash TV, the Monday Night Wrestling Wars, and peak PlayStation and Nintendo 64 were dominant while 1991 and 1992-borns didn't even enter their adolescent years until that era was either on its last legs or was pretty much over.