Maybe AIS is like identical twinning which also has a remarkably uniform rate. But in contrast to AIS, identical twinning is truly random where there is no increased incidence if the parent is an identical twin. Identical twinning has been hypothesized to be essentially a birth defect where the egg splits for some reason. Maybe AIS has a similar component like that. Maybe all IS is congenital.
AIS is said to follow very complex inheritance so something else has to be involved. Whatever that other something else is distributed fairly uniformly because there are not wild swings in the prevalence of AIS over the landscape.
AIS is almost certainly more than one thing. It is challenging enough to sort out other forms of scoliosis from AIS. But even after that is done, AIS may still have multiple etiologies. This is one of many reasons why the literature is probably not so good.
Sharon, mother of identical twin girls with scoliosis
No island of sanity.
Question: What do you call alternative medicine that works?
Answer: Medicine
"We are all African."