So by comparing how similar GCSE results are in identical twins versus nonidentical twins and doing some clever maths, we can get an idea of how much variation in performance is due to the environment, and how much is due to genes.
To znamo jer su u strogo kontroliranim  ekperimentima, kad učenicima damo materijal  za učenje ili u njihovom preferencijskom ili u onom  drugom stilu, nema baš nikakve razlike u količini  informacija koju zadrže.