Montoya, a psychotherapist who earned a master’s degree in social work at Fordham in 2005, had been organizing a closet in her New York City apartment while a Colombian TV station played in the background. She had grown up in Bogotá with an aunt and uncle who are fraternal twins and cousins who are identical triplets, so the topic of twins has always piqued her interest. But this report—about twins discovering at age 25 that one in each pair had been accidentally switched as babies—seemed too improbable to be true.

It was no soap opera. The Bernal Castro brothers, Jorge and Carlos, had been raised as fraternal twins in cosmopolitan Bogotá, while the Cañas Velasco brothers, Wilber and William, had been raised as fraternal twins on an isolated farm near La Paz. Neither set turned out to be biologically related. Through the detective work of mutual friends, it came to light that William and Carlos had been separated from their identical brothers, most likely in the hospital nursery. “I couldn’t stop thinking about it,” said Montoya, a licensed clinical social worker and the associate director of advising at Columbia University’s School of Social Work. “I couldn’t stop thinking this has to be a study.”

Because identical twins share 100 percent of their genes, they provide valuable information about genetic and environmental influences for medical and psychological research. The Colombian twins were even more ideal as research subjects since the two sets had been raised in starkly different settings, which opened a fascinating window into how identities are shaped by nature and nurture.

A Rare Research Opportunity

Though they’d never met, Montoya decided to contact Nancy Segal, Ph.D., a psychologist and behavioral geneticist known for her groundbreaking research on twins. Over the course of six rapid-fire emails, they decided to join forces on an extraordinary research project that resulted in the new book Accidental Brothers: The Story of Twins Exchanged at Birth and the Power of Nature and Nurture. Until the Colombia case, there had been only seven recorded instances of switched-at-birth twins. This was the first known case of two sets of identical twins being split up, reared apart, and then reunited as adults.

A practicing psychologist in Bogotá, Montoya came to the U.S. in 2001 to study at the English Language Institute at Wheeling Jesuit University in West Virginia. Missing big-city life, she moved to New York to attend Fordham. After graduation, she worked in varied settings as a clinical social worker, including with immigrant families and with September 11 rescue, recovery, and cleanup workers.

It took all of Montoya’s clinical skills, compassion, and resourcefulness to conduct the twin study. Segal laid out what she would need to do, which included personality questionnaires, health histories, IQ tests, more DNA tests, individual interviews, and small group discussions. In December 2014, she flew to Bogotá to meet the twins and ask them to participate in a study. They said yes.

A Tale of Two Upbringings

Jorge and Carlos were raised by a single mother and her close-knit family in a working-class neighborhood in Bogotá. Both attended good public schools and went on to college, where Jorge studied mechanical engineering and Carlos studied finance. Wilber and William grew up 150 miles from Bogotá on a farm with no running water or electricity. They attended school until they were 11, walking an hour each way over rough terrain. Then they worked full time on the farm. After compulsory military service, they worked at a butcher shop in Bogotá. That’s where a woman spotted William and mistook him for his identical twin, Jorge, her friend and co-worker. That encounter led the four to discover the truth, that the twins who grew up together weren’t twins at all—they weren’t even related.

The revelation upended their lives. Jorge and Wilber, who grew up with their biological families, worried about losing the close ties with the twins they’d grown up with. William pondered the hardships of his rural upbringing and the more difficult path he took to get an education. He eventually passed the high school equivalency exam and enrolled in law school in 2016.

Carlos grappled with the unanswerable question of what he’d be doing today if he’d grown up on the farm. And both William and Carlos dealt with the profound emotions that accompanied meeting new biological relatives as well as the fears that relationships with non-biological family members would change. In short, they were overwhelmed.

Brothers from Another Mother

In the spring of 2015, Montoya and Segal spent 10 days with the twins in Colombia. The most eye-opening part of the trip was a visit to the farm—not only for the research team but also for city slickers Jorge and Carlos. To reach the farm required a grueling hourlong trek through knee-deep mud. This was the key to understanding how much Wilber and William overcame to achieve what they had, Montoya said.

“When they experienced that, it was admiration for these children who had to do that walk twice a day in order to get a fifth-grade education,” she said.

After working with the twins, which way did Montoya lean—toward nature or nurture? Do genetics or environment matter more when it comes to upbringing and personality development? “I don’t think I’m into one versus the other,” she said, pointing to the book’s subtitle. “That’s why we use the ‘and’—nature and nurture.”

Montoya has been impressed by the resilience of the twins. All four refer to each other as brothers, even Wilber and Jorge, who have no familial or biological ties. Instead of focusing on the trauma of the situation, they’ve chosen to concentrate on what they’ve gained.

“They are really amazing muchachos,” she said.

—Mariko Thompson Beck is a Brooklyn-based freelance writer and a frequent contributor to this magazine.

Our genes are coded with explicit instructions for not only what we need to develop, said Alma Rodenas-Ruano, PhD, but also when each developmental process ought to begin.

That question of “when” is at the heart of Rodenas-Ruano’s epigenetics research, which she began as a researcher in the neuroscience department at Albert Einstein College of Medicine and has brought with her to Fordham’s laboratories.

“I’m interested in the neurological events that occur during what we call critical periods of development,” said Rodenas-Ruano, an assistant professor of biology. “As the name suggests, these are critical events that must happen for normal function to occur.”

Genes are subsets of DNA that define the fundamental traits an organism inherits from its parents. They are like a code that gives each cell instructions about what to do—for instance, to develop legs instead of fins or to start growing facial hair.

Epigenetics refers to cellular mechanisms cued by external events that influence whether or not a certain gene becomes active.

“The genetic code is set, but which genes are expressed or not expressed depends on the environment.” Rodenas-Ruano said. “For example, the first time an animal opens its eyes and lets light in, this sets off an epigenetic process of developing vision. If you deprive the eye of light, however, the normal development of those synapses will not occur.”

In the lab, Rodenas-Ruano uses zebrafish to study what happens to normal development if these epigenetic factors are changed or disrupted. Even small stressors, such as temporarily separating a newborn animal from its mother (and the same may be true for newborn humans, Rodenas-Ruano hypothesized) can alter certain epigenetic processes and gene expression as a whole.

“Disrupting this system causes mechanistic changes. The animal may behave normally, but if there’s another stressful event later in its life, that can trigger additional dysregulation in the system,” she said.

The potential benefits of her research could provide new insights for the treatment and prevention of neurological illnesses such as epilepsy or schizophrenia, Rodenas-Ruano said.

“Most diseases are multifactorial, and so we want to understand the exact triggers that make a person vulnerable,” she said. “We first have to identify and understand the basic mechanisms that contribute to normal function. Then, we see what happens if we disrupt these mechanisms—both what happens at first and what happens later on in a mature brain.”

Rodenas-Ruano, who just completed her first year at Fordham, is a recipient of a summer Grass Fellowship, a grant designed to support independent research projects by early career scientists. She is currently at the Marine Biological Laboratory in Massachusetts with a cohort of researchers from around the world. There, she is undertaking her project, “Epigenetic Regulation of the Cation-Chloride Symporter KCC2 During Neuronal Development.”

“This laboratory is a hub for neuroscientists. Many Nobel Prize winners have worked here. Hodgkin and Huxley discovered how neurons fire (action potentials) here,” she said. “They provide everything, from housing and equipment to a zebrafish facility.”

When she returns to Fordham in the fall, she will have her own zebrafish facility on campus. The space will allow her to involve her undergraduate students in ongoing research projects.

“These are challenging concepts, but my Fordham students have been well prepared and eager to learn,” she said. “I hope we can generate meaningful data and answer some questions about this topic.”