is what is proven to me time and time again in teaching little ones.
Parents every now and then will look at a class list and say "My child will be the oldest in the class and too far ahead of his/her classmates." or "My child will be older than her/his classmates and think that they are babies."
In reality their assumptions could not be further from the truth most of the time. The only child who can read in my room so far this year just turned 4. The youngest in my class last year was the first to be able to write her first and last name. Socially, some of the youngest that I've had are more together than the older ones.
To put assumptions on a child due to their age is a disservice to them. Each child develops at his/her own pace.