WASHINGTON — As society debates the ethics of cloning, scientists and ethicists say it is important to understand that cloning a human being could never produce an exact duplicate.
Everything from the cytoplasm of the egg cell where the DNA genetic blueprint is placed, to whether a cloned person remembered the Beatles would impose individuality on “borrowed” DNA.
Even identical twins, who are nature’s clones, are not totally identical. Clones made in a laboratory would be twins born years or decades apart, separated by generational and cultural chasms.
“By far the most mischievous misunderstanding is this idea that you can Xerox people,” said Harold Shapiro, president of Princeton University and chairman of the National Bioethics Advisory Committee which President Clinton has asked to evaluate the legal and moral dimensions of cloning.
“If you lost a child or parent, and wanted to bring a person back — you can’t do that,” Ian Wilmut, the scientist who cloned a sheep in Scotland, told a U.S. Senate panel last week.
Many experts, including Wilmut, are deeply troubled by the idea of cloning humans, a technology that could transform reproduction into replication; that could turn a parent and child into a pair of identical twins.
“If you take the DNA and, 20 years later, you put it in a different uterus, you couldn’t possibly replicate a person,” said Harvard University medical ethicist Lisa Geller.
“And if that’s what you’re trying to do, to replicate a person — you’re going to have a hell of a hard time with a teenager,” she added.
Ethicists, geneticists, biologists and psychologists argue endlessly about the balance of “nature” and “nurture” in human development, about which traits are inborn and which are shaped from environment and experience.
But even those experts tilting toward the “nature” end of the spectrum, like psychologist Thomas Bouchard of the well-known University of Minnesota Center for Twin and Adoption Research, say human clones would look alike, but would not necessarily be alike.
“The difference in temporal experience would magnify the difference in personality,” said Bouchard, who believes about half of psychological tendencies are inherited.
Environmental factors come into play from the very start. The cytoplasm of the cell into which the DNA is placed will be different from the adult cell from which it is derived. Small pieces of genetic material, known as mitochondrial DNA, will also be distinct.
And once the clone is implanted into a womb, the prenatal environment will differ as well. The diet of the woman carrying the fetus, whether she smokes, what chemicals or toxins she encounters in her daily life all affect the child.
“Identical twins are usually brought up roughly together, and treated in similar ways. But if the clone and source differ by a generation … all kinds of things change over a generation, what’s allowed, what’s taught, our diet,” said Philip Kitcher, a philosopher at the University of San Diego and the author of The Lives to Come: the Genetic Revolution and Human Possibilities.
A clone of Albert Einstein, taken out of 19th century Germany and placed, for instance, in late 20th century southern California would probably still be smart, and may well have the same wild white hair. But he would not necessarily become a physicist.
A clone of Michael Jordan would probably be tall, agile and have lightning reflexes. But he might not become a professional basketball player.
And a clone of any ordinary man or woman might look almost indistinguishable from the genetic parent, but could have a whole different view of the world, based on experience, luck or what theologians would call soul.
“Dolly (the cloned sheep) is a snapshot — not a snapshot of an adult sheep but one of that sheep’s cells,” said University of Pennyslvania bioethicist Glenn McGee.