I agree (having taught), but I disagree it's somehow genetic (which implies inevitable and irreversible). Most of the time it was a mismatch in prerequisites and a mental block like anxiety.

It can’t be not genetic. Just not totally I guess you meant. Or determinist as you said. As above said many factors but push genetic out is also not good.

Phineas Gage[1] would have limited ability, it doesn't mean he was genetically destined to get a rod through the brain. Weston Price[2] photographed and studied people around the world and wrote the book "Nutrition and Physical Degeneration" arguing that modern diets lead to physical development problems.

Not that it can't be influenced by genetics, or that people can all be the same; very few people will be Von Neumann reading a 46-volume world history series in his fifth language at age 8.

But saying "these people are failing at school, it's genetic" is a handwavy dismissal; a giving up on them. If it is, what should it change about teaching?

[1] https://en.wikipedia.org/wiki/Phineas_Gage

[2] https://duckduckgo.com/?t=ffab&q=nutrition+and+physical+dege...

If you have tutored one-on-one, you will surely have noticed that the difference in ability is miniscule compared to what can be taught by tutoring. Indian children do not have a genetic predisposition to spelling English words correctly.