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Conjoined Twins: Who Should Live and Who Should Die?

A 23 – year old has given birth to conjoined twins in Brazil. The two boys have separate brains and spinal columns, but share other major organs, including heart, lungs and liver.
The twins, who have dicephalic parapagus, an extremely rare disorder, are in a stable condition, and there are no current plans to surgically separate them. Doctor Neila Dahas of Santa Casa de Misericordia Hospital, where they are currently under care and observation, said, “it is impossible to take a decision with relation to surgery, not only because of physical reasons, but ethical ones as well.”

Another set of twins with dicephalic parapagus, Abby and Brittany Hensel, are now 21 and have never been separated. They are studying at University, and have each passed their driving test. They learned to walk, ride a bicycle and swim at normal speed.
Only four known sets of conjoined twins who share an undivided torso and two legs have ever survived into adulthood, and most have congenital heart defects or other organ anomalies

Conjoined twins vary in the degree to which they are connected. Sometimes they only connected in a minor way, by skin, and are easily separable. Sometimes they share vital organs and sometimes even their brains are joined.

From an ethical perspective, what matters is whether there are or will be two largely separate brains and minds. If so, they will grow into two separate persons or individuals, though in some cases they might share a body or vital organs, as in this case.

When should twins be separated? The obvious answer to this is when it is in the best interests, in terms of their future well-being, of both twins to be separated. The famous Siamese twin case of Chang and Eng Bunker was a case where they could now be separated but at that time, over a hundred years ago, they lived life connected. They went on to both be married and have children.

In the current Brazilian case, the situation seems ethically easy – it does not seem that separation is possible so they must remain connected.

The difficulty arises when separation is possible. In a widely publicised case in 2000, Jodie and Mary were conjoined. A court ordered separation which killed Mary, the weaker twin, in Jodie’s interests.

Lethal separation of infant conjoined twins can be ethically justified when the chances of survival or decent quality of life of one twin without separation is low, but the chances of decent quality of life of the other twin is high if separation is performed.

But in many cases, our law and judgements are ill suited to deal with this kind of case. Such separations do involve the killing of one twin to benefit the other. However, this is often put as allowing one twin to die, or by saying that one twin is using or is parasitic on the other twin. This is false. We have two individuals who share organs. The organs do not uniquely belong to one twin or another.

If such separations could be done during fetal development, they would be little different to selective reduction of multiple pregnancy, where one or more fetuses is aborted for the benefit of others. If selective reduction is permissible, lethal separation is permissible because the newborn infant is not significantly different in moral status to the fetus.

But it is important to recognise that such separations are infanticide. We should be open and honest in such cases that infanticide is occurring for the benefit of the other twin.

The situation is ethically very different once such conjoined twins grow and become competent persons. In such cases, separation can only occur with mutual consent.

In such cases, some separations kill both twins. This is an example again of permissible killing. Where both consent to the risks of death for the sake of separation, it is permissible.

What if one adult twin wanted to risk separation but the other did not? Here, one should err on the side of life. It is unreasonable for one person to be exposed to a significant chance of death to benefit another person, even their conjoined identical twin.

Thus we see the case of competent adults is different to infant conjoined twins. In one case, lethal separation for the benefit of one twin is impermissible but in the case I tis permissible.  Why is this? The reason is that infants are not yet persons capable of conceiving themselves existing across time, with hopes and plans for the future.

It is striking then that the law, in permitting lethal separations, implicitly accepts infanticide, just as it accepts feticide.

It is time to revise our laws on killing. Not only in cases of euthanasia and assisted suicide but also in our treatment of infants. Instead we prefer to redescribe such infanticide as not killing at all.

Many conjoined twins have gone on to live very good lives. Some separations were no doubt performed not in the interests of the twins but to conform to stereotypes of human existence, for personal moral or religious reasons, or out of disgust. Perhaps we should embrace human difference more and not separate such twins except where it is clearly necessary for the health and well-being of both twins, or not strongly against the interests of either.

The case of conjoined twins forces us to confront the ethics of killing and stereotypes of human existence. It is time to revise both.

Julian Savulescu discussed this case on NewsHour, BBC World Service

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1 Comment on this post

  1. Still on the topic of ethical issues with Brazilian babies:

    The news reported that "the first genetically selected Brazilian baby was born" some days ago. It was selected in way that it wouldn't manifest the genes for Thalassemia Maior, like his siter, thus being able to help her with the treatment :,nasce-no-brasil-1-bebe-selecionado-geneticamente-para-curar-irma,835877,0.htm (sorry, I couldn't find a non-Portuguese source for that).

    Now, I find this very interesting, and didn't know such procedures were legally possible. In fact, it surprises me that this haven't raised any discussion so far and that most do not seem to pay attention to it – this, I would like to point out, in a country where the congress is about to explode because a minister wants to merely " start talking about abortion".

    Then I found out something similar happened in the UK in 2009:

    Therefore, my question would be: would you know if this is a common procedure around the world? Or does it happen only in special cases, with special authorization and supervision?

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