The first, somatic cell nuclear transfer (SCNT), was the method used to make Dolly the sheep; it is essentially removing the nucleus from a somatic (non-reproductive) cell and replacing it with the nucleus from an egg cell, then tweaking the DNA so the hybrid was fooled into behaving like an ordinary embryo. The trouble with that method is that, chromosomally, the cell is already fairly old, so the year-old resultant clone is genetically several years older.
The second, embryo twinning (octupling?), essentially makes twins by hand instead of in utero. The scientist splits an eight-cell embryo (at which point its cells are still identical and capable of differentiating) into eight one-cell embryos. For research purposes, those new embryos are not allowed to mature enough to become future infants.
Now for a sampling of the ethical morass, resulting from inability of ethics to keep up with science, or from science overstepping its bounds. An inset on pages 94 and 95 explains "the bare bones of contention," which are (bold comments mine):
- Information. "Some of the loudest critics of embryo research...think the entity is the formed fetus, not an undifferentiated mass the size of the dot on the letter i. Other people may have less obvious misconceptions..." Yes. Does that make much of an ethical difference? I defer to the words of a sage on this topic. I may be oversimplifying too, but perhaps we need a little more of that.
- Premises. "Some disputants disagree about the value of that mass of [eight] cells, about how to define human life, and about when it starts." Is an otter not an otter when it's only two cells large? What about an eagle or another endangered species?
- Values. What is most important? Is it "progress in science," or "the needs of infertile couples," or is it the prevention of a slippery slope?
- Consequences. Perceived threats include "the continued lack of regulation of the private fertility industry," disappearance "of human dignity," and the uncertain future of IVF.