Education not meant for mass-consumption

Say you wanted to raise a genius. How would you go about doing that?

Assuming that your starting with an above average intelligence child with a greater likelihood of naturally becoming a "genius", can appropriate environmental/educational interventions substantially increase the child's potential for becoming one?

A couple of anecdotes say yes:

(1) Scott's review of "The Man From The Future" shows that Von Neumann, besides from obvious his obvious genetic advantage, benefited from growing up in a very resourceful family environment with rich exposure to top intellectuals & domain experts from all kinds of fields and private tutors.

(2) Laszlo Polgar's "Raise A Genius" suggests that the key is "early specialization" in a subject chosen under the parent's discretion (as long as the child enjoys the subject) in conjunction with 1:1 tutoring and having access to peers that are "mentally appropriate partners."

The field of behavioral genetic paints a somewhat different picture:

Most if not all psychological traits including intelligence being highly heritable, as long as you don't severely mess up your parenting (eg abuse, malnutrition), the specifics of your parenting strategy won't influence your child's outcome that much. Social/educational interventions just ... aren't as effective as one may expect them to be a priori.

But these two views aren't incompatible; some possibilities include:

Tail-effects in education: Since interventions have to scale, they end up being mediocre to "what could be possible." Perhaps having a Really Good Education (like what Von Neumann had) has disproportionate effects on one's life outcomes/genius-ness in a way that standard social/educational intervention RCTs can't capture.

Tail-effects in genetics: Just like how people with very low-intelligence seem to be fundamentally bounded in terms of the tasks they're capable of (regardless of the education they receive), a similar effect might be going on with normal intelligence folks where there's rapidly diminishing return to improved education—i.e. education scales better with individuals genetically predisposed to be smarter.

Both (1) and (2), where geniusness is a "leaky pipeline" in which you need both tail-end education and tail-end genetics to become a "genius."

What is the actual underlying dynamic of "genius production"? My hunch is that things are closer to (3), considering how Von-Neumann-type intellect is much rarer compared to the number of individuals that grew up having access to his level of resources. Also remember, the causal influence is bidirectional.

Also: does there exist prior work on "designing literally the Best Form of Education that's conducive to genius production" (provided that the child is genetically predisposed enough to actually benefit from them)? Longitudinal studies like SMPY comes into mind, but I don't know whether studies like these have been distilled enough to validate the practices of Neumann/Polgar, or produce novel insights for (non-mass-consumption) education.