DNA's 'Rungs' May Be What Makes Us Different

These changes, consisting of additions or omissions in the number of copies that the DNA makes of itself, were thought to exist in the form of "large-scale copy variations," but fairly rarely among normal individuals. That turns out to be wrong.

All together, the researchers studied 50 individuals and found that, on average, each person had 12 large-scale copy variations. That's a whopping number, especially if you try to imagine climbing a ladder with 12 rungs missing, and the researchers think those changes, which can extend over a considerable area of each genome, may help explain a lot about who we are.

More Rungs, More Disease?

It might even help scientists detect diseases much earlier. The most common variation involved amylase genes, which help the body break down starches, and Charles Lee of Harvard, co-principal investigator, finds that particularly intriguing.

"Our study shows that some people may have 10 copies of this gene while others may have as much as 24 copies of this same gene," Lee says. "It would be really exciting if we found that an increased copy number of these genes was associated with increased susceptibility to pancreatic diseases or cancer. This would allow us to use these (large-scale changes) as disease markers."

That could be a huge benefit in early detection of certain diseases.

But of course, all of this makes it sound like we're just a bunch of genetic robots, complying with blueprints that preordained that we would become just what we are. That's a common thought among geneticists and biologists, but Scherer, for one, disagrees. He still thinks our environment plays a major role in determining our uniqueness.

"It's the old nature vs. nurture debate," he says. That debate is being turned on its ear by research that wasn't possible just a few years ago.

"It's amazing how quickly things are happening in this field," Scherer says. "We're finding some traits that some of us, including myself, thought were entirely environmental, which in fact are almost entirely genetic. On the other hand, we're finding other things that we thought were genetic that are more influenced by the environment."

In the end, he says, if we ever really understand it, we will probably find that it is an equal measure of both that makes us what we are.

"A lot of the hardwiring is genetics," he says. "The reason you look like your parents is the genetics. But the environment really does tweak. You are programmed to develop to a certain height, but you may not achieve that because of nutrition changes, so environment clearly is going to be involved in tweaking some of the physical characteristics.

"But the behavioral? That's the real question mark. We don't know."

Do we act the way we do because of our blueprint? Or do mom and pop still make a huge difference?

It's probably both, Scherer says. "Everything seems to balance out in the end."

Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.

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