Jennifer Bricker was born without legs and immediately given up for adoption by her Romanian-American parents:
But with the support of her adoptive family, Jen, in spite of her physical challenges, grew to become a champion athlete herself. By age 12 she was excelling in power tumbling — an acrobatic sport that combines artistic gymnastics and trampoline. She failed to understand why people singled out her achievements over those of her teammates. In 1998, she placed fourth in the all-around event at the Junior Olympics, the first physically challenged tumbler to finish so high. Her gymnastics idol growing up? Dominique Moceanu.
Her gymnastics idol, Dominique Moceanu, was one of the “Magnificent Seven” at the 1996 Summer Olympics in Atlanta — and turned out to be her older sister.
Nancy L. Segal describes her work on identical twins and non-twin siblings:
I have studied separated twins for many years, first from 1982 to 1991 as an investigator with the Minnesota Study of Twins Reared Apart (MISTRA). Today, I follow the progress of 16 young Chinese reared-apart twin pairs, as well as older twins separated due to unusual life events. I have seen striking examples of identical, reared-apart twins whose athletic talents coincided prior to any contact between them. Japanese-born twins Steve and Tom, raised by different families in the United States, both became competitive lifters and owners of bodybuilding gyms; Steve competed in the 1980 Olympics. Adriana and Tamara, born in Mexico and raised in New York, attended different Long Island colleges and found each other only after one was mistaken for the other. But both were already accomplished dancers and later performed together. Mark and Jerry, each six-foot-four, were both already volunteer firefighters when they met in their early thirties, each having developed the strength, stamina, and motivation to pursue the demanding role.
Studying twins, particularly separated-at-birth pairs, and separately reared non-twin siblings, is the best way to disentangle the genetic and environmental influences on individual similarities and differences. For example, such research could help determine if nature or nurture is the stronger factor in sports participation and achievement. But other physical actions and routines appear to have a genetic basis as well. Most reared-apart identical twins in the MISTRA group, for example, positioned their bodies the same way while standing for unposed photographs, which occurred less often among fraternal reared-apart pairs.
A 2005 twin study by Dutch researcher Janine Stubbe showed that genetic effects on sports participation increase after adolescence, as children gain the freedom to enter and create environments compatible with their genetic proclivities. Her subsequent 2006 study confirmed this finding, and numerous twin studies from around the world have found similar genetic effects on oxygen uptake, anaerobic capacity and power, cardiac mass, and other performance-related fitness characteristics.
Claude Bouchard of the Pennington Biomedical Research Center in Baton Rouge, Louisiana, is one of the few researchers to combine twins and adoptees in genetic studies of sports-related traits. His 1984 study of submaximal physical working capacity — an index of aerobic metabolism and oxygen transport that boosts muscular activity and endurance — found the greatest resemblance between identical twins, followed by fraternal twins, biological siblings, and adoptive siblings and showed strong genetic influence on these traits. These findings have serious implications for how we make the most of our physical abilities and overcome our limitations.
Dominique and Jen are both extroverted, driven, and competitive. They are also perfectionists and “performance hams” who love being in front of a crowd. Their voices sound the same, whether speaking or laughing, and they use their hands a lot in conversation. Jen recognizes traits in Dominique that she sees in herself, such as leadership and initiative. Both are tough, detail-oriented, and able to push themselves emotionally and physically, perhaps explaining their commitment to the long hours and personal sacrifices required for success in gymnastics.
According to Dominique, though, an important difference between them is that Jen has “super-high confidence, whereas we were beaten down by our father. I walked on eggshells.” Jen herself credits her competitive success and self-esteem to the support of her adoptive family and community — and now to the DNA she shares with her sisters as well.
My reared-apart twin research reveals that close relationships can develop quickly between such pairs. In 2003, I found that over 70 percent of reunited identical twins and nearly 50 percent of reunited fraternal twins recalled feeling closer than or as close as best friends upon first meeting. These figures jumped to about 80 percent and 65 percent, respectively, for the closeness they reported feeling when surveyed. Yet only about 20 percent of the twins felt the same way toward unrelated siblings they had always known. In 2011, I reported my findings that most parents of young separated twins observed an immediate rapport between the children when reunited. These findings suggest that perceptions of similarity (mostly behavioral) are the social glue that draws and keeps reunited twins and siblings together, underlining the universal importance of family.