[anonporridge]

> We're comparing the typical outcome of a pair of parents with the best possible child those parents could have.

I'm still not sure I agree with this. There's huge variability between the reproductive fitness of siblings, even excluding genetic illnesses and deformities. Might be intelligence, body type, attractiveness, etc.

The real problem I see is that qualifying the "best" traits might be impossible, because what's best is highly subjective to the environment and the environment that we all live in is constantly shifting and seems to be doing so at an accelerating rate.

The film Gattaca actually gives an interesting take on how this drive for "best" might play out. Those born into the privilege of having the "best traits" a) don't feel as strong of a need to struggle and overcome adversity, b) dismiss people who are "lesser" than they are, and end up surprised and unable to compete when they fall behind, and c) people who are "lesser" are filled with motivation and drive to prove themselves. I could even see some parents intentionally giving their child a minor disability to give them an edge over their "perfect" peers who all flit their lives away thinking everything will be handed to them on silver platter. Similar to how some parents are starting to realize how damaging massive trust funds and inheritances can be to people that receive them.