Many people are confused about the difference between genotypes and phenotypes, and the relative effects of genetics versus environment in creating the latter. The genotype is the genetic information, and by Dawkins' "selfish gene" theory, this is what "attempts" to replicate itself. (I use quotes around the word "attempts" because genes don't really have any sense of purpose, or anything else.)

The phenotype is the body--the expression of the genotype in the physical world that is used to do the actual replication.

Much of the opposition to cloning stems from the assumption that the genotype is a blueprint , or specification for the phenotype, and fully describes the phenotype. In fact, blueprint is a poor analogy. Genes are much more akin to a recipe. That is, they're not a plan--they're a procedure. First grow this, here, next grow that there.

The difference is crucial, because if something is built to spec, it will, by definition, be very similar to another thing built to that same spec. A recipe, on the other hand, can come out dramatically differently, depending on the type of kitchen, available materials, the mood of the cook, etc. Two people can follow the same recipe and come out with different results.

The same applies to the expression of the genotype--the phenotype. Even identical twins have different retinal scans and fingerprints, so clearly they weren't built to a specification--there's nothing in the DNA to describe the exact configuration of the whorls and loops on the thumb.

What does this mean? It means that clones may, in fact, end up not being very similar to each other, meaning in turn that the fears about, e.g., armies of superwarriors are overblown. Identical twins share both genetics and the womb environment, so they are indeed close to identical, but even they will have distinct differences, as anyone who knows twins well can tell you. Two genetically-identical individuals gestated in entirely different environments may turn out to be dramatically different, to the point that it's not at all obvious that they're even related.

This has always been the theory.

Now apparently it's the practice as well.

The first cats to be cloned ended up not being, well, clones.

Question: can the difference be sufficiently large that, say, cloned organs may face rejection? Or is this something yet to be determined?

I don't think so, but I'm not enough of a microbiologist (i.e., not one at all) to say for sure. That would be a good question for Charles Murtaugh or Derek Lowe.

Okay, it's obvious that the first major environmental difference between the two editions of that DNA direction process was the two wombs...

But what if we "vat-grow" our clone army? That way they'll have the same environment, exactly -- just computer-control it. (I'll readily admit the tech just ain't even on the horizon yet.)