Foreign Bodies: As reproductive technology outpaces US immigration law, families struggle to stay together.

"The exile is a ball hurled high into the air. He hangs there, frozen in time, translated into a photograph; denied motion, suspended impossibly above his native earth, he awaits the inevitable moment at which the photograph must begin to move, and the earth reclaim its own."

—Salman Rushdie

It was on their third date, over dinner at a restaurant along the breezy metropolitan expanse of Rothschild Boulevard in Tel Aviv, that the question of family first bubbled up for Andrew and Elad Dvash-Banks. The year was 2008 and Andrew was in Israel on a student visa, working toward his master's degree in Middle Eastern studies. He was set to fly back home to Los Angeles for two weeks to celebrate his mother's upcoming wedding—"not her second or third," Andrew would later say, jokingly. For Elad, who came from a traditional Israeli family, this came as a surprise. "He had never really heard of somebody our age going to a parent's wedding," Andrew said. At one point, Andrew began drawing his sprawling family tree on the back of a napkin, hoping to "explain who's who." Studying the tree, Elad asked: "What kind of family do you see for yourself?"

It became clear as they talked that both men saw family—and children in particular—as an elemental part of their futures, a desire they were relieved to have in common. After a few months of dating, Andrew and Elad fell in love and moved in together in Tel Aviv. They finished school, traveled, built careers. The subject of kids dropped behind the scrim of their busy lives. The topic came up now and then, sometimes as a casual hypothetical about naming a future boy or girl, but it wasn't until Andrew and Elad were married in 2011 that they began seriously planning to have a family. "It really was a process," Andrew told me. "Deciding to have a family, for a same-sex couple, is just not something that you can do overnight and execute right away."

Choosing a place to call home and raise that family was its own challenge. At the time, Andrew could not marry Elad in the United States, or even sponsor him for a green card, because the Defense of Marriage Act—known as DOMA, and which defined marriage as the union of one man and one woman—was still in place. Canada, however, had legalized same-sex marriage in 2005. Fortuitously, Andrew, who was born in California, also held dual Canadian citizenship by virtue of his parents' Canadian origins. "We decided to give Toronto a shot basically by process of elimination," Andrew said. "That was one of a few places in the world where gay marriage was legal and we could actually live our lives as equal citizens—and I could sponsor Elad to immigrate."

Within a year of getting married, Elad began making calls to surrogacy agencies and lawyers just to try to understand the labyrinthine process of creating a family. They forecast for a lot: the emotional vicissitudes of in vitro fertilization, the financial burden of assisted-reproductive technology, the uncertainty of success. "It was so tumultuous during that period," Andrew said. "You worry: 'Am I going to be able to afford this?' and 'Oh my god, another $5,000 bill!' and 'Are the embryos going to take once we implant them?' and 'How many cycles could this take us to complete our family?'"

In 2016, they decided to take the next step. With the help of a surrogate and an anonymous egg donor, they fertilized two embryos to increase the chances of implantation—one egg with sperm from Andrew, the other with sperm from Elad. To everyone's surprise, it required only one cycle for both eggs to take in the surrogate. In September 2016, Andrew and Elad became the parents of twins, their boys, Ethan and Aiden, born just moments apart. They were exultant.

Not long after the boys were born—and with...