I'm pro-life but I have always been uneasy defining a "full human life" as beginning at conception, and this long before I had even heard of notions of stem cell harvesting and cloning.
When I read that Scripture talks about God knitting me together in the womb, I see it as a process not an event: that if I were to stop a woman from knitting a sweater a minute after she began knitting it, I would hardly be destroying a sweater.
Similarly, I consider God's formation of Adam in Genesis. He formed him from the dust, and then breathed life into him. Had God been somehow interrupted during the formation process, would the perpetrator be guilty of murder, or of an offense comparable to diving into a pile of freshly raked leaves?
Having said that, I've had the privilege of seeing an ultrasound of my own child only a few short weeks after conception---long before many people even realize they are pregnant. I would never have dreamed of intentionally harming that innocent life at this stage, nor would I like to see anyone else do the same to theirs.
During the travels from conceprion to exit into the uterus, the embryo takes on the appearance of a mulberry fruit, thus it is called a 'morula'. Twinning may occur from the totipotent and pluripotent cells of the morula. But the false 'christian' Archbissect is caliming a logical fallacy, that because a second individual may emerge from the morula package there isn't a first individual present in the morula package.
In science, the zygote is the first celled age of the entire lifetime of at least one new human being begun at fusion of parent chromosomes. Every cell from then onward, for trillions of cells, will have that same 46 chromosome identity ... but it is possible for a second or even third individual to arise from that 46 chromosome beginning and it doesn't negate the fact that at least one individual began at the fusion of the parent chromosomes.
Cordially,