Oh gosh, I didn't come to those conclusions myself! The problem with studying intelligence is, like another user pointed out, that we can't effectively study an individual from the moment of birth until death without breaching basic human rights. So, these studies of the origins of intelligence rely on a lot of self-reported data. The 49% genetic 51% stimuli number is, as far as I'm aware (please take this with a grain of salt), a widely-accepted statistic by psychologists to explain that intelligence is composed of inherited traits and learned traits, and that the learned traits are ever so slightly more significant in the outcome of a child than sole genetics.  I agree with you though; I took the most rigorous course program available at my high school, which had an application test similar to an IQ test but more holistic. Guess what? The test was a mere formality because everyone who applied was accepted to the program, since the school decreed that turning kids away for lack of aptitude was discriminatory and "ableist"... What a world. Anyway, hope my explanation was sufficient! http://www.apa.org/pubs/journals/releases/psp-824663.pdf