ENVIRONMENT AND GENETICS: CAN WE SEPARATE THESE TWO ASPECTS?

Before I go into the explaining the question, I would like to clarify couple of things. Firstly, being genetic and being inherited. If we say something is genetic that doesn’t means it’s inherited. But if we say something is inherited means it’s genetic.  In other words, if I say that some trait is genetic that doesn’t mean it will be inherited. For example, our eye color is inherited, which means it’s genetic.

  Secondly, In my discussion with Dr. L.S. Shashidhara couple of days back, I rose the same question which we all are pondering upon. Is intelligence genetic? He told me I should understand that, this question has different meaning in different context.

  According to him, Biologists look at intelligence as the ability of the brain to receive and process information. Biological basis of all learning and memory is dependent on how the brain is formed and developed (formation of neuronal network). Since all biological phenomenon are controlled by gene products (while at the same time influenced by the environment), one can say there is genetic basis for intelligence too.  This doesn’t mean that intelligence is inherited.(As I have explained the difference between being genetic and inherited).

 Educationists and social science people look at intelligence as ability to learn in schools and learn modern knowledge. This is largely dependent on learning environment, like peer group, teachers, teaching/learning methods etc.
Furthermore, new neuronal connections are made during our childhood. This is an evolutionarily-adapted strategy to prepare the brain depending on which environment you live. So a kid's ability to perceive and process information is more dependent on environment than genetic factors. The latter is important for the ability of neurons to send out their axons and to make synapses(.for more details) That is primary requirement.

http://www.nature.com/mp/journal/v16/n10/full/mp201185a.html ,this paper says intelligence is a multigenic trait(depends on functioning of many genes). Any such trait will show more variations than single gene-regulated traits(which is dependent on functioning of one gene). The probability that children inherit genetic ability of parents to learn and process information is very low. Mathematically speaking - we can say it is inheritable. But in real world, it has such low probability, the environmental influence masks genetic influence. 

According to me, we cannot separate the environmental and genetic factor because environment also affects our genetic makeup. This is precisely Darvin’s Theory of Evolution. For example, we all know that we don’t have a tail unlike our ancestors (more precisely genetically very closely related species have tails). This means that because we were not using our tail for long time (many generations) it got removed from our genetic makeup.

Finally, I would like to say that YES, in biological terms intelligence is genetic but it’s environment which dominates and mostly it’s environmental factor which matters because environmental factor can affect our genetic makeup. That is why I say that environment and genetic factors cannot be separated.