Nature Vs. Nurture

Image via WikipediaEveryone is familiar with the great debate over how we are shaped as persons. Some believe that most of who we are is shaped by our experiences and actions - if you grow up in an aggressive environment you grow up to be aggressive. At the same time there is a large contingent of people who believe who we are is built into us, programmed into our genes. Take for example the studies of identical twins separated at birth who end up in the same careers and have the same exact food preferences.

The way I always felt was that each person was born with many inherent characteristics (aggressive or tame, smart or stupid, honest or duplicitous) but that events could shape the extent to which these natures would be expressed. I imagine a fast moving river as the person, it has a natural tendency to go in a certain direction but can be redirected for a time by obstacles (events in life) which can alter the course of the river. I suppose the whole debate boils down to how fast you think the river is moving. The course of a slow meandering river would be much easier to shape - ergo people aren't destined to be good or evil, the events of their life determine this.

Recent Studies have thrown a monkey wrench in all of this it seems. They've shown that gene expression within the brain can be effected by social cues in life. In birds, hearing a new song by a male from their species changed what parts of their DNA asserted itself. In bees, the presence of many foraging bees prevented the foraging gene from being expressed in young bees. Take away the adult foragers and suddenly some of the young bees become foragers - genetically!

Is there even a genetic person anymore? Do we all have the potential to be many different types of people, only waiting for events to dictate to us which one we should be? I feel cut adrift now, this takes away my neat little metaphor for human development.

And finally, does this throw into question commonly held notions about evolution? According to the theory lifting weights everyday and getting huge muscles won't imply that your kids will grow up to be muscle men. But if events in life effect gene expression, is it possible that changes of this kind could be inherited? Anyone out there know enough about biology to answer this one? Best response in the comments gets a prize. Not really.