What is intelligence? If we are to ask the question about whether it is environmental or inheritable, we need to be clear about what intelligence actually is.
My old psychology teacher used to say “intelligence is what intelligence tests measure.” In other words, intelligence is what we decide to measure. It is a ‘man-made’ concept, and as such, fallible. Possibly wrong. Of course we measure the test against its ability to predict success within certain situations. In recent years because intelligence tests mainly predicted academic success, which didn’t ultimately predict success in life, other categories have been added to the concept of intelligence. Emotional intelligence, for example.
People are more or less capable of surviving within a given situation. Is this intelligence? A brilliant stockbroker may have great difficulty surviving in a war zone. A child who has grown up against a background of war, may be excellent at reading the nuances of his or her environment, but may have a brain that has been subjected to so much stress over a lifetime, that to survive in any other environment may be very difficult.
To some extent of course people have the potential to do well in certain areas if they are given the opportunity to do so, and that potential depends upon our inheritance. Sme have the potential to be wonderful tennis players or runners, some have a geat capacity for empathising with other people, some have a gift for acting or singing, and some have a gift for mathematics or language. Whether or not they will be able to use these gifts depends upon what they experience from the time of conception to the time that they take their last breath. It also depends upon the opportunities they are given and the choices that they make.