Magazine article Psychology Today

The Truth about Twins

Magazine article Psychology Today

The Truth about Twins

Article excerpt

The Truth About Twins

A new book by a prominent twin researcher debunks many popular myths and makes a strong case for how all of us can benefit from studies of identical pairs.

GIVEN THAT TWINS are more than 3 percent of the population, it's somewhat surprising that they're the subject of so many misconceptions. Tales of sibling telepathy, mate-swapping, and general eeriness have been with us for centuries. But as research into the origins and life experiences of twins has advanced, more debates can be definitively settled, and it's hard to imagine a better guide to that work than Nancy Segal, director of the Twin Studies Center at California State University, Fullerton, who has contributed to some of the field's foundational studies. Her new book, Twin Mythconceptions, is an entertaining investigation into the scientific basis, or lack thereof, for more than 70 commonly held beliefs about identical and fraternal pairs. These are matters of interest to a growing number of families-the rate of twin births in the United States has risen almost 80 percent since 1980, due primarily to advances in infertility therapies.


The topics Segal tackles range from curiosities to life-or-death questions. Can each member of a fraternal twin pair, for example, have a different father? Not only is it possible, but it's surprisingly common: The most recent study estimated that just under 5 percent of fraternal twin pregnancies involve the genetic contributions of separate men, but Segal contends that it's likely higher, since when the two dads are of the same race and ethnicity, mothers may just assume that both twins have the same sire.

No unusual prenatal events are required for twins to have different birthdays. The longest known interval between deliveries is a stunning 87 days. And twins' birth order matters, but not for the reason you might think: There's little proof, Segal writes, that being delivered first or second has any lasting impact on one's psychological outcome. On the other hand, secondbom twins are at a higher risk for health problems including respiratory distress, neonatal trauma, and infections than are their just-older siblings.

Young identical twins often seem to have a telepathic bond, but there's no evidence that it's real. Their similarities reveal something about the likeness of twins' minds, not a link between them. …

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