I don't know. Chalking things to luck seems... like an admission that we don't actually understand the causal factors that well. Especially combined with your other evidence that there was a clear delineation between folks with good/bad teeth.
Actually, your point about flour heavy diets basically sending folks that used to have perfect teeth to cavities sounds very not luck based. Which is it? Genetically some folks have cavities, or that common modern diets lead to cavities?
But it literally goes against the other argument. That isn't luck, that is prior choices having a larger impact than current choices.
If diet of the mother is important, we can start educating future mothers to have diets that help. Sure, there is no panacea for people with bad teeth today, but that is true for a lot of things we take corrective action on.
Getting into the existential weeds a bit here with free will and all, but that's OK with me. I'm not using a strict definition of purely random luck here. I'm using a looser colloquial definition under which choices by yourself or others can affect your luck. Like if the dictator chooses to chop off all heads with my hair color today, that's bad luck for me, even though he caused it. Or if I choose to drive drunk, and hit a utility pole, that's bad luck for me, even though I caused it!
Here's a trans-generational example: My dad makes a bunch of awesome choices that result in his becoming rich. Then I get born, and someday inherit that fortune. I'm much more inclined to describe my own outcome as luck than his, probably because my own decisions had less to do with it.
On the other hand it's not really so straightforward, because so many occurrences are attributable partly to random chance and partly to free will by somebody or somebodies. Maybe my rich dad benefited from luck, like not being crippled by polio or war, or not being born into a repressed social group. And of course my own "good luck" is a result of dad's explicit choices (your point), plus it also hinges on my own actions, such as not doing anything particularly atrocious to alienate him such that I get written out of the will. So is he a genius or just lucky? Probably a bit of both. Am I lucky or just shrewd/a good son? Probably a bit of both.
Ok, I was following "luck" as in "non-deterministic."
Pulling it back to what I think you are saying, though; there are still some obvious points that need more exploration for a causal factor. And if it can be found, then it should be exploited more.
So, if there really is a link between mother's diet and bone health, we should find out what that link is. If it is diet related, we should find out what about the diet leads to it.
I'll note my bias. I have the best teeth of my siblings. I likely have the worst brushing habits. Even in grade school, when I had braces, I would brush the night before the dentist, and would generally chew gum/whatever whenever I wanted. Easy to say I got lucky genetically. But what if there is more to it than that? What if my genetic luck was my allergy to damned near all food which knocked out some specific food that caused issues? (Would be almost poetically ironic if it was milk or some such.)
So, colloquially, I don't disagree that luck is a big factor. I just don't think luck should rule out looking for causal factors that can be exploited. Pretty sure that is standard for exploration/exploitation strategies in any learning scenario, no?
Yep it is, and we should most definitely nail it down with further study. Especially since, as you kind of hinted, it's so hard to isolate or control all the variables when you're dealing with people just living their lives.
Actually, your point about flour heavy diets basically sending folks that used to have perfect teeth to cavities sounds very not luck based. Which is it? Genetically some folks have cavities, or that common modern diets lead to cavities?