Please note that this is not US specific. I think that most Western countries apply similar principles when it comes to paying damages and I am looking for an answer that is as generic as possible.
Two adults with a certain defect to their vision (let's say astigmatism) decide to produce an offspring. The child then gets the same visual defect. Why can't the child sue her/his parents for damages to cover the costs for glasses and other aids (s)he needs to correct this problem?
I have asked around among lawyers and similar and they mostly try to avoid to answer.
The reason I ask about a visual defects is that, AFAIK, it isn't affected by lifestyle choices (e.g., diet, physical activity etc), it is purely genetical (yes, there are certainly exceptions but ignore them for now). Proof of burden is therefore a non-issue, it is all a matter of "causation" (I think that is the correct term).
The chain of events that lead up to the costs incurred by the child begins when the adult parents, voluntarily, decide to procreate and nothing the child, or any outsider, can do can prevent the child from getting this visual defect and having additional costs for glasses and similar aids.
The general principle in "tort law" is that if you perform some action that incurs a cost on someone you have to pay damages. It doesn't have to be intentional: if you go biking and for some reason fall and damage a parked car, you have to pay - even though you clearly intended not to fall. The only thing that matters is that there is a clear connection ("causation") between your action (biking and falling) and the damage to the car.
Isn't there a clear connection between the parents' decision to procreate and the costs the child has for glasses? And shouldn't the child therefore be able to sue for damages?
(I have of course bigger fish to fry than the costs for glasses, my question concerns the general principles, not the cost of the actual glasses.)
Edit: I wrote that it was not US specific but I understand that people who know law mostly know the law in one specific country so country specific answers are welcome, i.e., "In UK it would work like this", "In Italy it works like this" etc. I am interested in both the general principles but also local implementation.