Was Jesus an only child?

In the Book of Mark—one of the four canonical Gospels of the New Testament and the one believed by scholars to have been written first—there’s a passage where Jesus returns to his hometown of Nazareth to preach. The Gospel tells us that the people there were amazed, in part because they knew exactly who he was: “What are these remarkable miracles he is performing? Isn’t this the carpenter? Isn’t this Mary’s son and the brother of James, Joseph, Judas and Simon? Aren’t his sisters here with us?”

For centuries, this passage has been at the heart of a question in Christian theology: Did Jesus have siblings? More specifically, did Mary and Joseph have additional children together after Jesus was born? It’s a question that different Christian traditions have answered in radically different ways over the millennia—all while consulting the same basic texts. 

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Traditionally, both Catholic and Eastern Orthodox doctrine have upheld the idea that Jesus was the only son of Mary. Protestants, meanwhile, are historically more inclined to take the “brother” literally. The reasons for the different interpretations vary, but they’re intimately connected to centuries of translations and a millennia-old belief not just in the virgin birth of Jesus, but Mary’s lifelong chastity. 

The many meanings of ‘brother’

Jesus and his earliest followers would have spoken Aramaic, but the Gospels were originally written in Greek, a common language of the Mediterranean world at the time. The Gospel of Mark uses “adelphos” to describe “brother,” or the Greek word “adelphoi” in the plural.  

The word itself is not particularly difficult to translate, explains Bruce Chilton, Bernard Iddings Bell Professor of Philosophy and Religion at Bard College, who has worked extensively on early Christian history. “But of course, one of the interesting things that happens within the early Christian movement is that these very basic terms can be deployed metaphorically,” says Chilton.  

For example, in the Apostle Paul’s writings, he often addresses communities as “brothers,” even groups including women. “That’s why translators, when they look at this, don’t know what to do; sometimes they’ll say brothers and sisters,” says Chilton. 

But Chilton points out that’s not the context of Mark 6, either: “If you’re in the place where you’re brought up and people say, isn’t this the one whose brothers are—that’s not metaphorical. That’s in linguistic terms quite a direct designation,” he says. 

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“Adelphoi” doesn’t only appear in the New Testament’s Gospel of Mark. It’s in the Gospel of Matthew as well: Jesus is teaching when someone tells him, “Your mother and brothers are standing outside, wanting to speak to you. ”In response, he gestures to his disciples and says, “Here are my mother and my brothers. For whoever does the will of my Father in heaven is my brother and sister and mother.” The Gospel of John, meanwhile, recounts their initial skepticism. 

One brother appears in more detail: James, who would become an important figure in the early history of Christianity. Paul refers to him as “the brother of the Lord,” and he’s also referenced in the works of the Jewish historian Josephus, his contemporary, who refers to him as the brother of Jesus. 

“He’s a powerfully influential figure,” says Chilton, adding, “He was the leader in Jerusalem—not Peter, certainly not Paul.” He was ultimately killed around A.D. 62. 

Another sibling, Judas—also referred to as Jude, and not to be confused with the disciple who betrays Jesus—has traditionally been associated with the second-to-last book of the New Testament, the Epistle of Jude. “That doesn’t mean that we can claim direct authorship, although some people do,” says Chilton. We know little else, and even less about Simon and Joseph.

Why do Christians disagree about Jesus' siblings? 

The reproductive life of Jesus’s mother, Mary, is what has made this question so fraught in Christian history. Early on, an idea emerged that Jesus was not simply the product of a virgin birth, but that Mary remained chaste forever after—a doctrine known as the perpetual virginity.

An apocryphal text from the 2nd century, the Protoevangelium of James, played a key part in advancing that idea, explains Helen Bond, Professor of Christian Origins at the University of Edinburgh. It didn’t make it into the Christian Bible, but scholars say that it was influential in shaping Christian beliefs about Jesus, Mary, and Joseph, as well as affirming the Incarnation, Virgin Birth, and the Perpetual Virginity of the Blessed Mother. The text fleshes out the story of Jesus’s birth and background, portraying Joseph as a much older man with grown children. 

“What the Protoevangelium is obsessed with is Mary’s perpetual virginity. That’s what it really wants to explain,” says Bond. “Where do these brothers and sisters come from?”

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As theologians wrestled with the question of where these “adelphoi” came from, three positions emerged, all of them named for 4th century Christian thinkers, which demonstrates just how old this debate is.

The Helvidian view, named after the Roman theologian Helvidius, argues that Mary and Joseph had children together after Jesus. The Epiphanian view, named after Bishop Epiphanius of Salamis, sees these siblings as children of a previous marriage by Joseph. The Hieronymian view was named after St. Jerome, the man who translated the Bible into Latin. He argued that Joseph, too, was a lifelong virgin, and that these were neither Mary nor Joseph’s children, but cousins. 

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Eastern Orthodox theology has long accepted the Epiphanian view that these brothers were children of a previous marriage by Joseph. Meanwhile, the Catholic tradition has tended to take the view that these were cousins—pointing out, for instance, that in the Gospel of John, Jesus entrusts the care of Mary to his beloved disciple John, which wouldn’t be necessary if he had younger brothers. Both Eastern Orthodox Christians and the Catholic Church believe in the perpetual virginity of Mary, and the Catechism of the Catholic Church still affirms that Jesus was Mary’s only son. 

But many of the Protestant traditions that emerged in the wake of the Reformation in the 16th century elevated the importance of a direct relationship with Scripture. New Protestant denominations produced translations in the common languages of the time and focused increasingly on what was supported by the text itself, rather than longstanding church tradition. “Most Protestants are not worried about Mary’s perpetual virginity,” says Bond. “It’s not obviously Biblical.” Consequently, Protestant tradition is largely unbothered by the idea of younger siblings.

The case for a blended family

The modern scholarly consensus leans toward the likelihood that Mary and Joseph would have had a standard marital relationship, and that Jesus did have younger siblings, says Bond: “These children are Mary’s children, but born in the normal way to Joseph.” 

But scholars have argued that “adelphoi” could also have referred to Joseph’s children from a previous marriage. “Most families at the time were blended families,” Bond points out. This was a place with a very high mortality rate. “People died, women married again, men married again, so they came into a marriage with existing children. I doubt that anybody is making very hard and fast distinctions…. I think it really means those people about your age who grow up with you.” 

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Ultimately, both Chilton and Bond point to another important factor to consider, separate from the texts themselves: the simple demographic realities of the era, which point to the possibility of a blended family, rather than one option or the other. 

“We’re talking, including Jesus, of a family of seven grown children, at a time when it has been estimated by successive scholars that about 35% of all children born died by the time they were 5,” says Chilton. It’s tough to make the math work for all younger siblings, considering the number of pregnancies it would take to produce that many adults. “I’m not saying that all those named brothers or that the sisters came from Joseph’s first marriage, but that it only becomes plausible that they would be that number if there was in fact a combination,” says Chilton. 

“I think people tend to think Jesus came from a large family, it’s a little bit like it was in Victorian times, people had large families,” says Bond. But that’s not true, because mortality was so high. She points to census returns from Egypt, the neighboring Roman province, a rich trove of demographic data. “You can see quite easily that these are largely blended families—it’s a woman who’s got a couple of kids who marries a man who’s got a kid, maybe there’s another child.” Family size often looked more like two children than 12.

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Ultimately, any attempt to get a concrete answer runs up against the simple realities of the available evidence. “This is a rural family, low status, they’re artisans, craftspeople in a very small village in rural Galilee,” says Bond. Typically, they would have left light traces on the historical record. As such, we may never know the forensic truth; it will remain a matter of faith.