Large height difference in adult children- why?

[Lemonsareforlife]

Name changed as kids know I'm always on MN

I have 2 sons.
I'm 5 8 and DP is 5 11
One son was 6 feet tall at 15. He's now 20 and 6 feet one, size 11feet
The 18 year old is 5 feet 5 with size 5 feet. He has barely grown in years.
Same diet etc,

I can only think that he had an operation on undescended testicles at 9. I have HUGE guilt for not spotting this issue before.

Will DS ever grow? Have we left it too late?
DS is very very reserved and will not speak.
It's short for an adult man.

Maybe the op did something?

My elder son is 6' 5, his brother 6'1 and their sister 5'3. I'm 5'7, my husband about 5'8. My mum's parents, and her sister were all just over 5'2. My dad's family are taller, my gran was th same height as me. My husband's mum is the same height as DD, his dad about 5'11. However DH has someone who was very famous for being very tall.