Demographics
Adults
As of April 11, 2025, the Registry has 9,413 adult twin pairs (18,826 individuals). Below is a detailed breakdown of the Twin Registry population, calculated from the survey that twins complete when they join the Registry.
| Adult Age Group | % at Enrollment | % Today |
|---|---|---|
| 18–19 | 20.5 | 0.4 |
| 20–29 | 20.8 | 3.9 |
| 30–39 | 15.3 | 24.7 |
| 40–49 | 12.5 | 24.9 |
| 50–59 | 13.0 | 14.5 |
| 60–69 | 11.9 | 14.0 |
| 70+ | 6.0 | 17.7 |
Ethnicity
Hispanic/Latino: 3.8%
Race
White: 90.4%
Asian: 2.6%
Black: 2.0%
American Indian/Alaska Native: 0.6%
Pacific Islander: 0.4%
Other: 1.4%
More than one race: 2.7%
Zygosity
Identical: 53.3%
Fraternal: 46.7%
Sex
Male/Male pairs: 27.7%
Female/Female pairs: 50.7%
Male/Female pairs: 21.6%
Zygosity/Sex
MZ Male: 18.7%
MZ Female: 34.6%
DZ Male: 8.9%
DZ Female: 16.1%
DZ Male/Female: 21.6%
Youth
As of August 31, 2024, the Registry has 625 juvenile twin pairs (1,250 individuals). Below is a detailed breakdown of the Twin Registry population, calculated from the survey that twins complete when they join the Registry.
| Youth Age Group | % at Enrollment | % Today |
|---|---|---|
| 4 and younger | 70.9 | 9.1 |
| 5 to 9 | 24.0 | 31.7 |
| 10 to 14 | 5.1 | 44.5 |
| 15 to 17 | 0.0 | 14.7 |
Ethnicity
Hispanic/Latino: 8.5%
Race
White: 82.9%
Asian: 1.6%
Black: 1.0%
American Indian/Alaska Native: 0.5%
Pacific Islander: 0.3%
Other: 1.8%
More than one race: 12.0%
Zygosity
Identical: 54.7%
Fraternal: 45.3%
Sex
Male/Male pairs: 41.9%
Female/Female pairs: 40.0%
Male/Female pairs: 18.1%
Zygosity/Sex
MZ Male: 26.1%
MZ Female: 28.6%
DZ Male: 15.8%
DZ Female: 11.4%
DZ Male/Female: 18.1%