As of November 1, 2022, the Registry has 9,871 twin pairs (19,742 individuals). New pairs are enrolled on a quarterly basis. Below is a detailed breakdown of the Twin Registry population, calculated from the survey that twins complete when they join the Registry.
Age
| Age group | % at enrollment | % today |
|---|---|---|
| 9 and younger | 5.8 | 4.1 |
| 10-19 | 19.9 | 2.7 |
| 20-29 | 19.2 | 6.2 |
| 30-39 | 14.3 | 27.6 |
| 40-49 | 11.8 | 17.8 |
| 50-59 | 12.3 | 13.5 |
| 60-69 | 11.2 | 13.6 |
| 70+ | 5.7 | 14.6 |
Ethnicity
Hispanic/Latino: 4.0%
Race
One race: 96.9%
White: 90.0%
Black or African American: 2.0%
American Indian or Alaska Native: 0.6%
Asian: 2.5%
Native Hawaiian or Other Pacific Islander: 0.4%
Some other race: 1.4%
Two or more races: 3.1%
White and Black or African American: 0.5%
White and American Indian or Alaska Native: 0.8%
White and Asian: 0.9%
Two or more other races: 1.0%
Zygosity
Identical: 53.2%
Fraternal: 46.8%
Sex
Male/Male pairs: 28.6%
Female/Female pairs: 49.9%
Male/Female pairs: 21.6%
Zygosity/Sex
MZ Male pairs: 19.2%
MZ Female pairs: 34.0%
DZ Male pairs: 9.4%
DZ Female pairs: 15.8%
DZ Male/Female pairs: 21.6%