Babies with three parents are no longer the stuff of science fiction. A British ethics board has just approved an experimental treatment that results in babies with genetic material from two women and one man. Also, there's evidence that babies born using egg and sperm donors receive genetic input from more than two parents.


There's no denying that reproductive technology is changing the ways we define parenthood. But will it change families too?

The Science of Three-Parent Families
One of the immutable laws of nature seemed to be that babies are born from the mixture of genetic material from a man and a woman. But now there are a few ways that science is putting a kink into this equation.


Earlier, I mentioned an experimental procedure that could create babies with three genetic parents. This procedure is designed to help women who suffer from heritable diseases that are passed on via small pieces of genetic material in the main body of the cell. Most genetic material in your cells is packed into the tiny nucleus at the very center of the cell, but a few pieces of it reside in cell organs called mitochondria that float around in the cell outside the nucleus. The problem is that the child inherits all its mitochondrial DNA from its mother, which means that mitochondrial diseases are hard to shake from one generation to the next. In this procedure, doctors would take healthy donor egg cells, scrape out the genetic material inside the nucleus, and replace it with the mother's DNA. Presto — a baby will be born with the donor mother's mitochondrial DNA, plus nuclear DNA from mom and dad.

Even babies who are the result of sperm or egg donors may have genes that are shaped by three parents. Epigenetics is a new field that explores how genetics are shaped by environment. For example, a fetus with healthy DNA could still be born as a child with birth defects if the mother smokes cigarettes while pregnant. The environment she creates in her womb changes the way the fetus' DNA behaves, and this happens in many subtle ways. So it isn't at all outlandish to claim that the woman who carries a fetus affects the future child's genes, even if the child carries DNA only from an egg donor and the father. The fetus' genetic expression is affected by the womb where it grows.


Parents and Bioparents
Advances in fertility treatments over the past several decades have meant that we've already had to change what we mean when we call somebody a parent. It is now common for parents to talk about biological parents, often shortened to "bioparents," as well as parents. The bioparent donates genetic material; the parents are the ones who rear the child. Depending on the arrangement, bioparents may actually play a role in the children's lives. Other times, the bioparent is a kind of ghost figure that nobody wants to talk about.

Surrogate mothers may also fall into this bioparent category, though their status can be even murkier because she may or may not have contributed any genetic material. Still, even if the fetus' DNA comes from the parents, we know from epigenetics that the surrogate can influence how that DNA gets expressed.

I also think it's worth noting that the bioparent/parent distinction also has resonance for blended families and divorced families. Sometimes the parent who has contributed genetic material to a child is absent. A new marriage can bring parents into the child's life who aren't bioparents, but who nevertheless contribute meaningfully to the task of raising the child.


And then there are two parent families that couldn't reproduce without inviting a third bioparent into the mix. A friend of mine who has been married for several years recently told me what it was like getting her wife pregnant. At the fertility clinic, my friend was allowed to steer the instrument that's used for insemination — let's call it a turkey baster, for old time's sake. Thanks to reproductive technology, and a friendly environment at the clinic, she was able to participate in making babies with her wife. And of course she'll be a parent to their children. Gay parents are by necessity creating children with three parents, or two parents and one bioparent.

What Is A Parent, Anyway?
Ultimately this begs the question of what it means to be a parent. Are bioparents simply contributing some genetic material to the "true" parents? Obviously it depends on your perspective. Some people strongly believe that a genetic connection between two people gives them some kind of relationship, no matter what. It's this belief that fuels kids' desires to meet their bioparents, and vice versa. It's motivated the development of open adoptions, where the bioparents have some access to their biochildren, even if they have no legal relationship with them.


As three parent families become more common, we may find ourselves redefining a lot of words we thought were pretty much immutable, like "parent" and "family." After all, it may not be appropriate to call some of these three parent arrangements "families" if the bioparent never has any contact with the children. Indeed, some parents would no doubt object to my referring to egg or sperm donors as "parents." And I have no argument with any of these ideas — families should be what we make of them.

Indeed, three-parent families should remind us forcefully that families are not bound by biology. Our parents may not be genetically related to us. They may not be a man and a woman. They may not be two people at all, but a group of people who contributed to our genetics and our rearing. People in blended families might have two bioparents, but also two parents; plus they'll have a batch of biosiblings and siblings. And of course some people have single parents, too.

Not all of these changes are the result of science. As I mentioned earlier, the growing acceptance of divorce and blended families has contributed to questions about what it means to be a bioparent versus a parent. More recently, gay marriage has raised the same kinds of questions. What we're experiencing today are concurrent shifts in reproductive science and social norms around the family. It's not clear where all these changes will leave us. But what is certain is that the rise of three-parent families means more children being born into loving homes that would once have been childless. That fact alone has changed forever what it means to be a parent.


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