So often in life as well as in science, things would just be easier if they were this or that, black or white, nature or nurture. But like life things just aren't so simple. Right up on the top of the list of non-simple things is our brain. With about 100 billion neurons, that each have between 1 and 1,000 connections to other neurons, our brain is extremely complex.
So it is necessary to balance what genes and neural connections we come into this world with and the experiences and environment that brings out the best in them. Although we often hear that a new gene has been found to blame some ill on, it is so rare that one gene is responsible for anything all on its own. The environment, our personal choices, and our experiences go a long way in determining if a gene will be show up in our life or not.
A great metaphor put forth by Dr. Alvaro Pascual-Leone for this balance of genetics and choice is a snowy hill. Dr. Pascual-Leone says it so well:
“The plastic brain is like a snowy hill in winter. Aspects of that hill--the slope, the rocks, the consistency of the snow--are, like our genes, a given. When we slide down on a sled, we can steer it and will end up at the bottom of the hill by following a path determined both by how we steer and the characteristics of the hill. Where exactly we will end up is hard to predict because there are so many factors in play.” (Doidge, 2008)
As any of us who have gone sledding know, once you make that first track down the hill, you tend to follow back down it again the second time. And trudging back up the hill you tend to follow that same set of footprints back up. Dr. Pascual-Leone goes on to talk about after sledding all afternoon you will have some tracks that are very hard to get out of.
We have the power to guide our brain and the tracks it follows. Just because I may be predisposed to heart disease because of my genetics doesn't mean I have to follow that track. I can instead choose to fill my environment with healthy foods, exercise and keep that gene from taking control.
Doidge, N. (2008). The Brain That Changes Itself. Penguin Group USA. p 209.