Conjoined Twins in Halacha

The Tosafists do not cite the conclusion of this Midrash, but other sources do. R. Betzalel Ashkenazi (1520–1592)14 relates that King Solomon covered one of the heads with a linen cloth and poured boiling water on the other. In response to the pain, both heads screamed out, proving to the wise king that the two-headed entity is indeed one person and not two.
Similarly, R. Yehuda Aryeh Modena (1571–1648)15 writes that he heard that Solomon used boiling water to determine whether both heads feel the same pain. R. Yosef Chaim of Baghdad (1832–1909) writes16 that what R. Modena wrote was an incomplete version of the Midrash. To supplement the story cited by the Tosafists, he cites the conclusion found elsewhere: Solomon asked for a linen cloth, hot water, and aged wine. He covered one head with the linen cloth and began to pour the hot water and aged wine on the other head. Suddenly, both heads screamed out, “We are dying! We are dying! We are one, we are not two! We will no longer say we are two people.”

R. David Ganz (1541–1613) writes in the name of the Roman historian Dio Cassius (155–235) that in the time of the Roman Emperor Antonius Pius (86–161), a woman gave birth to a boy that had two heads.7 R. Matisyahu Strashun (1817–1885)8 writes that he is inclined to say that this person is the child mentioned in the Talmud who was born in the time of Rebbi (a contemporary and friend of Antonius).9 However, R. Yitzchak of Vienna (1200–1270) writes that the Talmud sometimes refers to fantastic phenomena that do not really exist, and cites Plimo’s question as an example of such an occurrence.10

Writing in Hakirah vol 26 (Spring 2019, p. 259), R Reuven Chaim Klein (‘Till Death Do Us Part: The Halachic Prospects of Marriage for Conjoined (Siamese) Twins) identifies three options whether or not such twins would be allowed to marry

• In the first approach (based on R Akiva Eiger), the twins are considered two different people and, by virtue of the attachment to each other, cannot get married because they will always cause the other to violate an ervah-level sexual prohibition (having relations with one twin would be considered having relations with the other)
• In the second approach (according to R Yaakov Reischer), though they are technically considered two different people, they still cannot get married because of similar ervah concerns (having relations with one twin would violate the prohibition of having relations in front of another or of approaching an ervah)
• In the third approach (based on the Ben Ish Chai), the two are considered one person and completely assume the position of the more dominant twin, which means conjoined twins should be allowed to marry

Rabbi Chagiz’s rulings R. Yisrael Yaakov Chagiz (1620–1674) writes: “I remember that I saw in Italy32 a gentile—about twenty-five years old—who was born attached to his twin until his waist, chest adjacent to chest, and from there they were attached. And he was mobile and completely like any other person. The smaller [twin]'s head is inclined towards one side and his feet were hanging downwards and reached to the knees of the larger [twin] and he did not have any feeling at all [in the attached part of his body], rather it was like a limb whose senses have been dulled and he lived many years with his twin.”33 Three questions were raised: 1> If one murders the smaller twin, is the murderer liable or do we consider the smaller twin halachically non-existent? 2> Does we circumcise such a child? 3> How does this person live? The first two questions are purely halachic, while the last question is scientific. R. Chagiz opens his responsum by answering the last question first. He asserts that the smaller twin is sustained through the liver of his twin brother which filters and sends blood to his liver, just as a mother’s liver (and placenta) performs that function for her unborn child in utero. Regarding the smaller twin’s halachic status, R. Chagiz argues that this person has the halachic status of a goses (a moribund individual), but he is nonetheless circumcised. R. Benzion Alkalei (1858–1913),34 disagrees with this last ruling, arguing that if such a person is considered a goses, then surely he is exempt from the commandment of circumcision. One cannot even move a goses, let alone surgically remove his foreskin. R. Chagiz also discusses whether or not one should recite the benediction mishane habriyot upon seeing such a person and whether or not this child is entitled to a portion in his father’s inheritance. While not discussing conjoined human twins, per se, R. Chagiz was also asked about how to view the existence of conjoined chicks: QUESTION: In Verona, they showed two chicks that were attached from the side. It appears that they came from two different egg yolks. They had two heads, two necks, four feet, and both heads were able to eat. What is [the halachic status of this chicken (i.e. may it be eaten and how)]? ANSWER: It is a creature from the Six Days of Creation. According to the opinion that Adam was created thusly35 [i.e. Adam and his partner originally formed one back-to-back person], the other animals of creation were also possibly created so.36 If they [the chickens] live for twelve months, you may37 slaughter both heads like one (so as not to [invalidate the slaughtering by way of] waiting [in the middle of slaughtering]) [and the chicks may be eaten].

An animal upon which the act of bestiality is committed assumes the legal status of a nirba (animal used for illicit cohabitation) and is thus disqualified from ritual sacrifice. The Talmud53 rules that if one cohabits with a pregnant animal, not only does the mother assume the status of nirba, but so does her offspring. The Tosafists54 write that even according to the opinion that “a fetus is not the thigh of its mother,” both the animal and its issue are disqualified. Drawing from this precedent, R. Akiva Eiger (1761–1837)55 understands that any time a man engages in sexual activity with a pregnant being—animal or human—he effectively cohabits with the fetus in utero, as well. Thus, R. Eiger asks: How can a man cohabit with his pregnant wife, if by doing so he may effectively be cohabiting with his own daughter (if the child is female)? R. Eiger resolves this issue on a technical basis. The Talmud56 rules that sex with a female human under the age of three does not have the legal status of sex. Therefore, even if by cohabiting with one’s wife one is considered to be cohabiting with his daughter, the Biblical prohibition of incest does not apply because she is less than three years old. Although incest with a girl younger than three is technically permitted according to Biblical law, doing so is nonetheless forbidden by Rabbinic fiat under the umbrella prohibition of the wasteful destruction of semen (because a girl that young cannot yet conceive). Based on this, R. Eiger argues that since cohabiting with one’s pregnant wife is certainly not considered the wasteful destruction of semen (even though she generally cannot become pregnant again),57 the Rabbis never decreed that one should refrain from doing so. Therefore, even though by engaging in relations with his pregnant wife, a man may be halachically cohabiting with his own unborn daughter, such an act is completely permitted because the daughter is certainly younger than three years old and there is no prohibition of wasting semen.58 R. Eiger’s entire treatment of this issue is predicated on an assumption relevant to our discussion about conjoined twins. It seems that both his question and answer59 assume that because one’s unborn daughter is attached to his wife, then his wife should somehow become forbidden to him—even if we say “a fetus is not the thigh of its mother.” This author infers from R. Eiger’s responsum that he understands that if a permitted woman is somehow attached to an incestuous relative, then even sex with the permitted woman is prohibited at an ervah-level. In the case of conjoined sisters, if one sister is married to a man, he should become prohibited from cohabiting with his wife because she is attached to the ervah of his wife’s sister (achot ishto). Conversely, if the conjoined twins are brothers, then the wife of the married brother should be forbidden to her husband because he is attached to her husband’s brother (eshet achiv).60 Problems with R. Akiva Eiger Nonetheless, the assumptions R. Akiva Eiger makes in his discussion and the conclusions we drew from those assumptions are not unanimously accepted. It is related that R. Chaim Soloveichik (1853–1918) held R. Eiger in great esteem and once remarked that R. Eiger never proffered any convoluted logic, save for two cases. One of those two cases is the above-mentioned discussion in which R. Eiger questions how one can be permitted to cohabit with his pregnant wife. The basic premise of R. Eiger’s question extends the Talmudic assertion that one who cohabits with a pregnant animal disqualifies both the animal and its offspring from being offered as a sacrifice to the realm of sexual prohibitions between humans. However, in truth, R. Soloveichik argues that the Talmud only means to extend the disqualified status to the offspring, but does not mean that the prohibited act is considered to have been done to the offspring as well. Thus, R. Soloveichik rejects R. Eiger’s application of said Talmudic principle, instead limiting it only to the case in which it was explicitly used.61 Furthermore, R. Yisroel Yaakov Fischer (1928–2003)62 writes that he does not even understand R. Eiger’s opening question63 because sexual prohibitions outlaw intercourse only in the sexual organs. Therefore, even if copulating with one’s pregnant wife is, in some way, tantamount to engaging in sex with the unborn child attached to its mother, this should not be considered a violation of any sexual prohibition. Nonetheless, this difficulty has already been addressed by R. Akiva Eiger’s son, R. Shlomo Eiger (1785–1852),64 who explained that the sexual prohibitions of the Torah do not simply outlaw certain acts of intercourse; rather, they forbid deriving certain sexual pleasures from forbidden unions.65