Not true at all . School years start from September to August.
What's that got to do with a kid born in January being 10 months older than a kid born in November?
They would be in different school years .
Not necessarily. For example, I was born in May 1983, yet I was in the same class as kids born in June-December 1982, and Jan-April 1983
They were all older than me, but same age group for any school sports
Exactly. The people born in the last 4 months of the year have the advantage .
MMV said people born in the earlier part of the year have an advantage which just isn't true . you even proved it with yourself as an example ! !