Catholic apologist Tim Staples gives an excellent answer to the question “do clones have souls?” (h/t The Deeps of Time):

Once an embryo has been created through Somatic Cell Nuclear Transfer (the cloning process) using a human egg and human somatic cell, a new, living organism comes into being that is biologically, genetically human (note: this has been done before – here and here). There absolutely is no reason to believe that such a human being would not have a soul.

But some people don’t agree.

A few years ago I had a meeting with then Governor of Missouri Matt Blunt – an anti-abortion Republican, but an avid supporter of human cloning research. His rationale for supporting the creation and destruction of human life via cloning for embryonic stem cell research was that he didn’t think these cloned embryos were “human life.” He explained that he believed that God’s plan for the creation of human life involved the union of a sperm and egg and, while he agreed with me that a new “life” would be created through SCNT, he disagreed that that life would be human because since no sperm would be involved in the creation process and so there would be no human soul. When I asked him to explain, then, what kind of organism was actually created he said more or less, “we don’t know what it is, but it’s not human, is therefore not unethical and should not be banned.” Though, he did think that there should be a ban on actually implanting these “non-human” organisms and bringing them to birth. Hmm…

Interestingly, not too long ago I had a conversation with my deeply religious Grandfather who is opposed to human cloning, embryonic stem cell research and IVF because that believes that the only proper context for the creation of new human life is within the marital act – as God ordained it. That’s not the interesting part. What’s interesting is that he also believes, much like Blunt, cloned human embryos would not have souls. In fact, he goes even farther than Blunt in this regard as he believes this about any human life created outside the marital act. I tried to explain to him that, whether created with a sperm and an egg via IVF or using a human egg and somatic cell, SCNT, these organisms would be genetically and biologically human, indistinguishable from one created through normal, in utero, sexual reproduction. Not only that, but there are thousands of these human beings, created via IVF, living in the world today. That didn’t seem to make much difference. He was pretty adamant that God would not infuse a rational human soul into something created outside of His grand Design. I love my grandpa, and I agree that human cloning and IVF are abominations, but, for the life of me, I cannot understand how he can believe that there could be such a thing as a soulless human being (whose name isn’t Nancy Pelosi – I keed!).

Very often, whole question of “ensoulment” is used by the pro-choice/pro-ESCR/pro-cloning camp to confuse the issue of when human life begins and justify the destruction of life in its earliest stages (see this St. Louis Post article for an example). But, John Paul II explains why it is important to ALWAYS err on the side of life – from the very beginning:

Even if the presence of a spiritual soul cannot be ascertained by empirical data, the results themselves of scientific research on the human embryo provide “a valuable indication for discerning by the use of reason a personal presence at the moment of the first appearance of a human life: how could a human individual not be a human person?” … Furthermore, what is at stake is so important that, from the standpoint of moral obligation, the mere probability that a human person is involved would suffice to justify an absolutely clear prohibition of any intervention aimed at killing a human embryo. Precisely for this reason, over and above all scientific debates and those philosophical affirmations to which the Magisterium has not expressly committed itself, the Church has always taught and continues to teach that the result of human procreation, from the first moment of its existence, must be guaranteed that unconditional respect which is morally due to the human being in his or her totality and unity as body and spirit … (Pope John Paul II, Evangelium Vitae 60, On the Value and Inviolability of Human Life – emphases added)