TABLE 1.
Demographic and descriptive statistics for the Vietnam-Era Twin Registry sample
| Monozygotic twins(n = 3932; 1966 pairs) | Dizygotic twins(n = 3058; 1529 pairs) | P | |
| Age (y) | |||
| Young adult | 20.01 ± 1.631 | 19.99 ± 1.58 | 0.532 |
| Middle age | 40.66 ± 3.11 | 40.61 ± 2.75 | 0.49 |
| BMI (kg/m2) | |||
| Young adult | 22.01 ± 2.93 | 22.09 ± 2.94 | 0.57 |
| Middle age | 25.99 ± 3.73 | 26.10 ± 3.70 | 0.82 |
| Race [n (%)] | 0.553 | ||
| White | 3682 (95) | 2862 (95) | |
| African American | 169 (4) | 131 (4) | |
| Hispanic | 0 (0) | 2 (0.1) | |
| Other | 14 (0.1) | 4 (0.1) | |
| Social contact [n (%)] | <0.001 | ||
| Almost daily | 958 (24) | 306 (10) | |
| Weekly | 1112 (28) | 654 (21) | |
| Monthly | 1120 (28) | 940 (31) | |
| Yearly | 674 (17) | 1056 (35) | |
| Less than yearly | 68 (2) | 102 (3) |
1
Mean ± SD (all such values).
2
t test.
3
Chi-square test.