Absolutely true both ways.

I was advanced 2 grades (1st to 4th) so was easily the youngest kid in my class. Read ‘also the shortest, slowest, least coordinated, and weakest boy’. Over years some classmates who were a year or so older than average had mustaches as I started puberty.

Everyone forgot that as a freshman in HS I was 13! I was only 5’ 2”. I was mocked & bullied by many boys and ignored by all the girls that didn’t bully me.

Then I finally grew between Junior & Senior year. I also spent that summer as a lifeguard and got contacts.

Senior year I start first day 6’ tall, tanned & fit, wearing contacts. I had 8-9 popular/pretty girls come up and introduce themselves and offer to show me around since I must be a transfer student.

Oh, the looks when I told them who I was!