Table 1.
Descriptive statistics.
| Variable | Siblings of children who have a DD who were born 1990–95 (SDD1990) |
Siblings of typical children who were born 1990–95 (STC1990) | Siblings of children who have a DD who were born 2000–05 (SDD2000) | Siblings of typical children who were born 2000–2005 (STC2000) |
|---|---|---|---|---|
| Total number of siblings | 9,807 | 565,033 | 8,488 | 315,939 |
| Number of sisters (percent of total siblings) | 5,056 (51.56%) | 277,184 (49.06%) | 4,140 (48.77%) | 156,901 (49.66%) |
| Number of brothers | 4,751 | 287,849 | 4,348 | 159,038 |
| Mean number of children in the family | 1.06 (S.D. 0.24) Range 1-3 |
1.12 (S.D. 0.41) Range 1-7 |
1.32 (S.D. 0.47) Range 1-3 |
1.22 (S.D. 0.46) Range 1-5 |
| Income quintile of the reference child at birth | ||||
| Lowest | 1,169 (27.10%) | 57,527 (22.08%) | 1,193 (25.16%) | 49,542 (21.77%) |
| 2nd | 914 (21.19%) | 55,449 (21.28%) | 1,017 (21.47%) | 48,413 (21.28%) |
| 3rd | 812 (18.82%) | 53,388 (20.49%) | 957 (20.21%) | 46,452 (20.42%) |
| 4th | 759 (17.59%) | 50,919 (19.54%) | 849 (17.93%) | 44,057 (19.36%) |
| Highest | 660 (15.30%) | 43,264 (16.61%) | 720 (15.20%) | 39,074 (17.17%) |
| Sisters with a diagnosis of depression (number and %) | 2,363 (46.74%) | 65,340 (23.57%) | 882 (21.49%) | 14,442 (9.20%) |
| Sisters with a diagnosis of a mental health problem (other than depression) (number and %) | 2,443 (48.32%) | 63,004 (22.73%) | 1,110 (27.05%) | 19,171 (12.22%) |
| Brothers with a diagnosis of depression (number and %) | 1,620 (34.16%) | 47,783 (16.60%) | 658 (15.13%) | 12,731 (8.01%) |
| Brothers with a diagnosis of a mental health problem (other than depression) (number and %) | 2,338 (49.21%) | 66,304 (23.03%) | 1,462 (33.62%) | 26,455 (16.64%) |