Is a clone really a clone? Is Dolly an exact, flawless reproduction of her only parent -- who supplied her genes? Granted, she's close. Maybe we're quibbling, here, but it seems in the midst of all this hoopla that we owe you some quibbling. But there are several reasons to think she won't be exactly, precisely, utterly like her parent. First, even though all her chromosomes came from the nucleus from the adult sheep, Dolly's mitochondrial DNA still came from the egg donor. The mitochondria are cell organelles (defined) that help the cell process energy. (Mitochondrial DNA comes solely from the mother; since it never combines with the father's DNA, it can be analyzed to trace the evolutionary lineages of animals.) Second, the immune system genes are not fully developed at the embryo stage. "The genes that encode molecules of the immune system -- that make T-cells (defined) and antibodies (defined) -- continue recombining (defined) after fertilization," says Leder. Thus a clone would have a slightly different immune system than its parent. You wear jeans, but you aren't only genes. Third, environment also has its effects, and despite the uncanny similarities between identical twins, they are not fully identical, particularly when they're raised separately. Experiments with rats have proven that upbringing influences brain biochemistry, says Frank Farley, a psychologist at Temple University. When rats were randomly assigned to various environments, ranging from a bare cell to a cell full of rodent toys guess what? In terms of brain biochemistry, the enriched rats were different than the ones raised in sensual poverty. "This shows that the environment can influence the brain," Farley says. "And from other lines of research, we suspect that much of our human behavior is related to the biochemistry of the brain." Norm Fost, a University of Wisconsin-Madison medical ethicist, insists that the focus on genetics understates the importance of environment. "You can create someone with the same genetic makeup, but who you are is a function of your environment, too. A clone is not going to be a perfect replica of the adult, since alterations in environment, starting in the womb, influence which genes get expressed, and how the body and mind develop. To say Michael Jordan is just a function of his genes is an insult," he adds. A clone of Jordan would not make a basketball great -- dedication and a love for the sport would also be required, as well as the opportunity to play a lot of hoops. "If we had cloned Einstein," Farley adds, "depending on the upbringing, the clone might not be identical to Einstein." But look at the bright side. Maybe a Hitler clone would not develop into der Fuhrer. Indeed, in the movie "The Boys from Brazil," a frightening fictional story of cloning of history's arch-demon, the cloners not only used the same swap-the-nucleus technique that Wilmut used, but they appreciated the role of environment in the upbringing of the clones. Still, as we said before, this is partly quibbling. In the popular mind, cloning is already associated with complete, perfect reproduction -- and that's not too far from truth. We need to look at some legitimate uses for the cloning cloning technology.

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