1 ,I dont think it is a fact .
2, there is no percentage of an influence to be able to measure,is there?
3, as us humans who can communicate and be educated to do so do...the gap from 1 to another in a percentage differing of no more than 25% if say a proffessor is 100%,any greater a gap and a carer is needed...so your 75% is just how it is from dad to son brother mother neigbour teacher green grocer ect IMO.
I think it depends on how the child is raised..If the child,from young age, is tought to play chess alot and it's tought to think hard ,than the child's intelligence will be higher...If you're reffering to 75% through the genes and influented from birth,I don't think it matters.
i think that "theory" is fairly reliable since stupid people can't teach peope to be smarter and since it's proven that most kids spend more time with mom than dad. if your mom's a idiot your chances of being smart are reduced
I have actually never heard of that before