The Last 2000's birth year that went to high school with 90s borns?
Im not talking being in same grade but rather being together in highschool at the same time. So this will differ, depending on your region. But in my region it's 2004 borns, they were the last birth year that went to highschool with 90s borns (1999) this is because high school is 6 years here, from ages (12 to 18)