Yeah, this reminds me of a somewhat chilling moment when a chinese teenager asked me what I was reading about (regression to the mean).
By way of introducing the concept, I asked "if someone is very tall, are their parents probably taller or shorter than they are?" "Shorter". So far so good.
"If someone is very short, are their parents taller or shorter?" "Shorter".
Apparently, to the current generation, no matter how short you are, your parents are shorter. Long live the CCP :/
As people get older, their height gets shorter. It's not entirely wrong to believe that your parents will be shorter than you, no matter what your height is.
This process has limits. Older chinese aren't short because they're old, they're short because of nutritional stress.
Also, shrinking isn't a linear process. You spend most of your life only shrinking a small amount; most of it happens toward the very end:
> For both sexes, height loss began at about age 30 years and accelerated with increasing age. Cumulative height loss from age 30 to 70 years averaged about 3 cm for men and 5 cm for women; by age 80 years, it increased to 5 cm for men and 8 cm for women.
It's saying it took until the 1930+s for European men to reach levels of height we'd consider normal for teenaged girls today.