Table 1.
Sample Characteristics
| Pairs |
Child age |
Mom age |
Child's ethnicity |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Zygosity-sex | n | % | M | SD | M | SD | % Caucasian | % Hispanic | % Black | % Asian | % Mixed-other |
| MZ male | 138 | 22.9 | 9.57 | 0.55 | 37.56 | 5.63 | 19.6 | 46.4 | 9.4 | 8.7 | 15.9 |
| MZ female | 139 | 23.0 | 9.66 | 0.61 | 38.54 | 6.92 | 21.6 | 38.1 | 12.2 | 4.3 | 23.7 |
| DZ male | 84 | 13.9 | 9.64 | 0.60 | 39.88 | 5.74 | 28.6 | 31.0 | 15.5 | 2.4 | 22.6 |
| DZ female | 97 | 16.0 | 9.55 | 0.55 | 39.43 | 5.29 | 35.1 | 32.0 | 17.5 | 2.1 | 13.4 |
| DZ male-female | 147 | 24.3 | 9.58 | 0.59 | 39.90 | 5.90 | 31.3 | 36.1 | 17.7 | 3.4 | 11.6 |
| Total | 605 | 9.60 | 0.58 | 38.98 | 6.03 | 26.6 | 37.5 | 14.2 | 4.5 | 17.2 | |
Note. Age of biological mother is shown, to allow comparison across zygosity groups for maternal age at birth of twins. Mean age of all caregiver participants was 40.14 years (SD = 6.61). MZ = monozygotic; DZ = dizygotic.