ORLANDO, Fla. (Ivanhoe Newswire) -- In the past few years, we've heard a lot about the mapping of the human genome, and scientists are frequently announcing their discoveries of genes for specific diseases. But does this guarantee a certain behavior or disease? Is this the case or can we overcome bad genes?

At the time we're conceived, two sets of genes combine to make one. In that split second, is our future sealed? UCLA immunologist William R. Clark, Ph.D., says no. He says all genes really control is how we interpret our surroundings. "You're dealt a particular hand of neurotransmitters and neurotransmitter receptors and again together, with other things of course, in your biology and in your history, it's going to play out differently in different people," he tells Ivanhoe.

He says the environment constantly changes the neuronal pathways that guide our behaviors. This unpredictability, he says, allows us to overcome genetic predispositions because we have the responsibility of choosing what to learn and how to learn it.

Like Clark, Harvard University's Steven Pinker, Ph.D., says genes alone do not dictate our behaviors. The environment we live in and reactions from others add to how we behave. "Even if you have more of a tendency to get angry than someone else, when you'll get angry and what you'll do about your anger is going to depend on how other people react," he says.

Developmental psychologist David S. Moore, Ph.D., of Pitzer College in Claremont, Calif., says behavioral tendencies, hereditary conditions, and even genetic diseases can only develop given the right environment. "If you are prone to be an alcoholic, there are environments on earth where you can put yourself where you will not be exposed to alcohol, and you will very quickly not be an alcoholic anymore." He says all characteristics need both genes and environment to exist.

"The fact that you have genes is almost irrelevant, because what really matters is which genes are turned on and which genes are turned off, and different genes are turned on and off in different circumstances."

Those circumstances, though, may be incredibly subtle. Space studies show, without gravity, some viruses develop differently. A diet free from phenylalanine can keep the metabolic disease PKU from developing, and research from Duke University shows a mother's diet can even change hair color in mice. So, even though identical twins are born with the same genetic blueprint, and often have similar experiences, no two environments will ever really be the same.

"Twin A has twin B in his environment, and twin B has twin A in his environment. They're not in the same place," Moore says.

And despite being treated like one, twins like Nancy and Janna Sipes are quick to point out they're unique. "The fun twin, and the less fun twin," they say. "Or, the serious one maybe? OK, that's better." Differences scientists will no doubt continue to try to explain.

As scientists gain a better understanding of what genes code for certain diseases, they're getting one step closer to fighting diseases like Alzheimer's before they have a chance to develop.

If you would like more information, please contact:

William Clark, Ph.D.
UCLA
wclark222@cs.com

David S. Moore, Ph.D.
Pitzer College
David_Moore@pitzer.edu

This article was reported by Ivanhoe.com, who offers Medical Alerts by e-mail every day of the week. To subscribe, go to: http://www.ivanhoe.com/newsalert/.