Registry members participate in studies focusing on the pharmacokinetics of nicotine, metabolism of commonly used medications, genetic susceptibility to cancer-causing chemicals, and sleep patterns in young twins.
Do you know any twins? Please consider sharing this page with pairs of identical or fraternal twins. We are especially interested in twins who live in the San Francisco Bay Area.
Join the Registry
Identical and fraternal twins (mixed-gender or same-gender pairs) of all ages are sought for the Registry:
- Adults aged 18 and over: Register online or call SRI at 1-800-SRI-TWIN (1-800-774-8946). By registering, you will be eligible to be invited to participate in studies. Most studies offer payment for your participation.
- Youths under age 18: Parents or guardians, please call 1-800-SRI-TWIN (1-800-774-8946) or print and mail this registration packet to register your twins. (As a precaution, we ask that you do not register a minor online.) Youths younger than age 18 comprise 15% of total registrants.
Current Studies (recruiting now)
- In-utero smoke exposure study: Identical or fraternal twins whose parents smoked while their mother was pregnant with them (one or both twins should themselves be nonsmokers).
- Smoke exposure and asthma study: Adult identical twins are needed for studies aimed at looking at the impact of tobacco smoke exposure on the immune system and asthma.
- Flu vaccine study: Identical and fraternal twins aged 12 to 49 and identical twins 2-5 years old are needed to help investigators better understand the genetic components of the body’s immune response to the flu vaccine. Recruiting will resume in the summer for appointments through early December 2015. Read an SFGate article about the study.
2013 Health Survey
Thank you to all of the twins who completed the Twin Research Registry 2013 Health Survey. A total of 1,285 adults completed the full survey, which included 438 pairs of twins (look for survey results in our next newsletter). Pairs were eligible to be entered into a drawing for a Kindle Fire HD e-reader; twins Sabra and Nina were our lucky winners. Congratulations!
- Twins were included in a Stanford-University led study aimed to determine which aspects of the immune response to the shingles vaccine are influenced by genetics Read more on PNAS.org
- In partnership with Stanford University, we examined the genetic and familial aspects of pain sensitivity
- Examination of the renal clearance of the commonly used prescription medication metformin (used in treatment of diabetes) in identical and fraternal twins to determine the role of heredity
- Comparison of the pharmacokinetics of the medication digoxin (a heart regulator) in identical and fraternal twins to determine whether inter-individual variability is due to genetic factors
- Examination of the extent to which genetics and environment affect sleep in children
- Investigation of the role of genetics in response to cancer-causing agents
- Investigation of whether the predisposition for cigarette smoking is related to how fast the body eliminates nicotine
- Testing of a biometric recognition technique to capture three-dimensional facial images in identical twins
About the Registry’s Name and Logo
The name of the Twin Research Registry™ at SRI International reflects our goals to be progressive, inclusive, and innovative in our research efforts.
Our logo was designed to represent the individuals and twin pairs that are so important to our research studies. The logo originated from the symbol for "person" in Chinese characters. The design symbolizes multiplicity, connection, bridging, and networking. It also hints at SRI’s Northern California location, but it flows openly to reach out to the rest of the world. The combination of colors is meant to evoke trust, confidence, wisdom, dignity, enthusiasm, fascination, and strength.
The Twin Research Registry at SRI International is an active registry of twins of all ages and backgrounds, fraternal and identical, who are interested in learning more about twins and to participate in research studies to help advance science.
For more information on twins research and twin registries, watch these presentations by Dr. Gary Swan:
- Twins: Unlocking the Secrets of Nature-Nurture Interactions Part 2