Alana Saarinen’s face resembles her mother’s. But her eyes, she says, are her father’s. So far this biological lottery sounds familiar enough (“You have your mother’s voice,” we often say, or, “You smile just like your father”). Except Alana’s story is different: While our DNA can traditionally originate in only one of two options—mother or father—Alana’s originate in three.

“I also have DNA from a third lady. But I wouldn’t consider her a parent,” Alana, who is 13, told the BBC last year.

Alana is one of less than 50 people in the world known to have DNA from three different people. Some of her mitochondria—which can be thought of as each cell’s power plants—came from a female donor who isn’t her mother.  

In the coming decades, as public policy increasingly reflects shifts in the future of health and technology, we will likely see many more advances in medicine that challenge our notions of traditional biology--and many more children with stories like Alana’s.

The procedure that added a third parent to Alana’s DNA, known as cytoplasmic transfer, was banned in the U.S. in 2001, though some U.S. research in the area continues. Earlier this year, the U.K. became the first country in the world to legalize this form of in vitro fertilization, which involves inserting the nucleus of the mother’s egg into that of the donor in order to prevent certain fatal genetic diseases that originate in the womb. The whole process takes less than an hour.

Medical experts and couples who have problems conceiving or who are prone to have babies who suffer from genetic diseases have praised this pioneering method. “What this means is that mothers who would otherwise be likely to have unhealthy babies with severe disabilities can instead give birth to healthy babies,” Michael Rimington, the medical director of the South East Fertility Clinic in the U.K., wrote in The Telegraph in 2013. Alana’s mother, for example, had tried to conceive unsuccessfully for ten years before undergoing this procedure.

But while many welcome the new law and its implications for the future of fertility treatment and genetic disease prevention, it has also produced an outcry by opponents critical of what they view as society’s first steps to a future of “designer babies.” Critics of the procedure cite a “slippery slope” when it comes to ethically uncharted questions.

Even if this procedure is regulated and medically sound, they argue, it could encourage the approval of others that are ethically murky.

There is no simple formula when it comes to parenthood or what constitutes a family. But with growing numbers of child adoption, IVF treatments, and now this groundbreaking “three-parent” procedure, intent will surely play a larger role in the families of the future—even more so than genes.

What this new law does highlight, however, is an issue that is certain to play out ever more publicly in the years to come: As technology advances, society will have to reevaluate age-old concepts such as parenthood and family. As a New York Times op-ed predicted in 2010:  “When technology transforms a legal field — as the Internet is doing now for privacy, and digital music and video are doing for copyright — judges and legal thinkers have to decide what are the important values.

A similar debate will play out in the field of DNA modification of human embryos, which some experts have begun to warn against for fear of ethical breaches. While science continues to forge ahead through such still-unmapped territory, it will be up to society to decide where the ethical boundaries are.

As for Alana, she is growing up as a normal, healthy girl. “"I couldn't ask for a better child,” her mother said. “She is an intelligent, beautiful girl inside and out.” Alana even helps around the house, her mother added. Then paused. “When she's not texting!”

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