[stephc_int13]

The only reason that tutoring is not more widely used is because it has scaling issues.

You need one very experienced, patient and skilled tutor for each kid. The cost would be unbearable except for the wealthiest families.

And of course, while it will consistently improve the skills and mental abilities of the tutored kid, it won't produce a genius every time, there are many out-of-control factors, including genetics but also related to early life, bacteria and viruses infections can slow/stunt the growth of an immature body, and impact all its functions.