2 fetuses fuse together


I have heard that it is possible for 2 fetuses to fuse together, and that is often why people have extra body parts, such as an additional set of teeth. I really have no clue about the science behind this, but I have a question about the unborn children. Do they both have a soul?



That opens up a whole new can of worms.

Call the press. We have another problem for the ITC.


Pretty much not going to even get an answer on that question! :shrug: (I’ve taken Embryology courses at my university, so this is real I might add.) There are some other really, really weird things that lead to some crazy moral questions as well.

But, unless you die and go to heaven and ask God, :wink: , your not going to get an answer on earth. (Well some moral theologians might speculate.)

Oh and I might add that fusion of twins is VERY rare, there have only been like a dozen cases in the past century. It also happens really early on.


Also, fusion of twins, has NOTHING to do with having an extra set of teeth! :smiley: That’s just do to a birth defect. What you see more often is that one embryo will die in-utero and then the other embryo will absorb some parts of it, such as extra arms, legs, mouth. This is a more clear morally because the other baby died, so there is nothing morally wrong with having extra legs, etc removed. This isn’t very common.

Also the extra teeth, fingers, etc is usually just due to faulty embryonic development.


Two brains=two souls


It’s not that simple if know much about fused twins.

However, it’s basically a non-issue, because it’s really rare, there are only like 2 medical cases of this in the US.


Okay, that is probably what is actually being referred to when people talk of fetuses fusing together. That clears some things up.


I know, my response was oversimplified, in the case of fused brains. :confused: Then it becomes an unanswerable question. :frowning:


Google “chymerism.” You’ll find out more than you ever wanted to.



Yes, two embryo’s can fuse together completely.

As another poster pointed out, one embryo can also die and just like a fusing of two embryo’s, the living embryo can fuse parts of the dead one to it’s body.

In the same way, an embryo as it is first conceived is not a twin. At a certain point in the process(very early on), a single embryo splits to become two embryo’s.

Since a soul is considered whole, and indivisible, this would indicate the soul is not created at the exact moment of conception.

Already said on this thread, we will never really know, until we die and are able to find out. Given current science however, and current definitions of the human soul, the soul does not appear to be 'created" as soon as the little sperm sets off some fireworks in the egg :slight_smile:


Two people means two souls. But if one dies first, the situation is a lot less complicated.


Actually, many moral theologians would disagree. The CCC indicates that the soul is immediately created by God, not by the parents (I think that’s 366). I don’t see why/how this is such a hard question…

1 egg + 1 sperm = embryo/zygote = 1 soul
embryo/zygote splits, at the moment of the split = 2 souls (God immediately creates the 2nd one)
embryos/zygotes fuse, at the moment of the fusion one ‘dies to self’ = 1 soul goes to God, the other remains w/ the fused embryo/zygote
siamese twins, at the moment of creation = 2 souls
siamese twins, at the moment of death of one = 1 soul goes to God, the other remains w/ the live twin

God is not limited by human minds, science, knowledge, detection, etc. He knows all, is in all, and sees all as it happens. There’s absolutely nothing that indicates that God doesn’t know the fusion or spliting of an embryo(s) is going to happen. At that moment, just like the moment of conception, God can (and probably does) impart the ‘breath of life’/soul into the embryo(s). Why not? Will we ever actually know? NOPE - I’ll make sure I ask God when I die though! :wink:


Which would mean that the dead child’s soul is in heaven and the living child has a soul.


This theory greatly weakens the argument against abortion, because you hold that there can be a “clump of living cells” with its own unique human DNA residing in the mother’s womb, yet for some reason it doesn’t have a soul anymore, and could presumably be removed by doctors without moral objection. How do expect Catholic doctors to distinguish between clumps of living cells that have a soul from those that do not?

It is far safer, morally speaking, to suppose that any “clump of living cells” having its own unique human DNA always has a soul. If a baby is born with an extra appendage resulting from fusion with a twin that occurred inside the mother’s womb, the only acceptable moral choice is to leave that appendage intact. Removing the appendage so that the appendage dies is murder just as surely as abortion (which is just removing the embryo so that the embryo dies) is murder.

Note that this is always the case if the fused twins started off as fraternal twins. If the fused twins started off as identical twins, it isn’t clear if the original single embryo/zygote ever split long enough to have a separate soul.


How can you distinguish between a living fingernail on my finger, and a living fingernail taken away from me and grafted onto another person’s finger?

Nobody is worried that my fingernail is somehow still mine when it’s been made part of somebody else. So why would you worry about it when it happens naturally?


By DNA, of course. Not that it matters, as the Catholic Church has yet to proclaim that fingernails have a soul and/or are deserving of the full rights due a complete human person.


Because all fingernails, by definition, are dead. There is no living tissue in a nail. :smiley:


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