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Twins Research

With their similar genetic makeup, twins represent an ideal opportunity to study health and behavior issues. From twin studies, it is possible to determine how genetic and environmental factors influence health. Studies can also provide scientific insights into twins and genetics, including conditions such as diabetes, heart disease, and obesity, as well as the effects of alcohol and tobacco use. By identifying the genetic components of these health problems and others through twins research, it is possible to develop early interventions and treatments.

For the National Institutes of Health and other clients, researchers at SRI's Center for Health Sciences conduct twins research studies on the pharmacokinetics of nicotine, the metabolism of commonly used medications, genetic susceptibility to cancer-causing chemicals, and sleep patterns in young twins.

The continually growing and diverse Twin Research Registry at SRI International™  includes more than 3,000 members who volunteer to participate in SRI twin research studies.

Twin Facts and Figures

Fascination with twins is part of every culture -- and dates back centuries. Some interesting twin "facts and figures" include:

  • In ancient times, doubleness in nature was often interpreted as a manifestation of the supernatural or intervention by the gods -- that is why many gods in different religions are twins or supertwins.

  • In the Aztecs, Babylonian, Zuni and Ashanti cultural myths, twins took the form of warriors, builders, healers, symbols of light, water or thunder.

  • Native American tribes in the Northwest believed that twins were actually salmon in human disguise.

  • The frequency of twin births reported vary from country to country and range from 1 in 80 to 1 in 140.

  • When it comes to phobias -- like fear of heights, of closed spaces, or of open spaces -- twins often respond similarly. Twins often share phobias, and more often than not if one twin harbors an irrational fear, the other does too.

For more information on twins research and twin registries, watch these videos about "Twins: Unlocking the Secrets of Nature-Nurture Interactions": Background on twins research and an overview of Twin Registries from Dr. Gary Swan's talk at Cafe Scientifique Silicon Valley.


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Twin Research Registry at SRI International

SRI established the Twin Research Registry as part of its scientific research and efforts to discover more about human behavior. Fraternal and identical twins and multiples of all ages are invited to join the Registry for consideration for research studies.