Table 1 Sample characteristics, separately for intervention and control condition
|  | Total (N = 202) | Intervention group (n = 83) | Control group (n = 119) |
|---|---|---|---|
Twin characteristics | |||
 Age at baseline 1 in months M (SD) | 45.07 (6.81) | 44.89 (7.44) | 45.20 (6.37) |
 Gender (% boys) | 45 | 45.8 | 44.5 |
 Country of birth (% Netherlands) | 99.5 | 100 | 99.2 |
Family characteristics | |||
 Primary parent (%) | |||
  Biological mother | 91.6 | 88.0 | 94.1 |
  Biological father | 8.4 | 12.0 | 5.9 |
  Age primary parent M (SD) | 36.87 (4.69) | 36.89 (4.82) | 36.82 (4.62) |
  Age second parent M (SD) | 38.49 (5.64) | 38.39 (5.69) | 38.56 (5.62) |
 Country of birth (% Netherlands) | |||
  Primary parent | 96.0 | 98.8 | 94.1 |
  Second parent | 96.4 | 97.5 | 95.6 |
 Educational level primary parent | |||
  Primary school | 0.5 | 1.2 | 0 |
  Lower vocational education | 4.0 | 4.8 | 3.4 |
  Higher general secondary education, pre-university education, intermediate vocational education | 25.7 | 31.3 | 21.8 |
  Higher vocational education, BA | 42.1 | 36.1 | 46.2 |
  MA, postgraduate level | 27.7 | 26.5 | 28.6 |
 Family SES | |||
  Low | 6.4 | 7.2 | 5.9 |
  Medium | 38.6 | 42.2 | 36.1 |
  High | 55.0 | 50.6 | 58.0 |
  Number of children in the family M (SD) | 2.80 (.76) | 2.87 (.79) | 2.75 (.74) |
 Primary parents’ marital status (%) | |||
  Married or registered partnership | 70.3 | 63.8 | 74.8 |
  Cohabiting | 26.2 | 32.5 | 21.8 |
  Single parent | 3.5 | 3.6 | 3.4 |
 Family type (%) | |||
  Biological parent(s) | 97.5 | 98.8 | 96.6 |
  Parental reactive temperament M (SD) | 4.31 (.72) | 4.23 (.67) | 4.37 (.75) |
  Parental psychopathology symptoms Wave 1 | 1.26 (.29) | 1.21 (.24) | 1.30 (.32)* |
  Parental psychopathology symptoms Wave 2 | 1.30 (.34) | 1.24 (.26) | 1.34 (.38)* |
  Parental psychopathology symptoms Wave 3 | 1.28 (.29) | 1.22 (.24) | 1.33 (.31)* |