From: Prevalence and heritability of handedness in a Hong Kong Chinese twin and singleton sample
 | Item | Preference | Twins | Singletons | Total | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Item | total |  | Male | Female | χ2(df = 2) | Male | Female | χ2(df = 2) | Twins | Singletons | χ2(df = 2) |
 | r | Class | N = 187 | N = 197 |  | N = 220 | N = 204 |  | N = 384 | N = 424 |  |
 |  | LH | 13 (7.0%) | 14 (7.1%) |  | 16 (7.3%) | 9 (4.4%) |  | 27 (7.0%) | 25 (5.9%) |  |
1. Writing | .717 | NP | 4 (2.1%) | 0 (0.0%) | 4.26 | 3 (1.4%) | 5 (2.5%) | 2.17 | 4 (1.0%) | 8 (1.9%) | 1.37 |
 |  | RH | 170 (90.9%) | 183 (92.9%) |  | 201 (91.4%) | 190 (93.1%) |  | 353 (91.9%) | 391 (92.2%) |  |
 |  | LH | 15 (8.0%) | 13 (6.6%) |  | 16 (7.3%) | 12 (5.9%) |  | 28 (7.3%) | 28 (6.6%) |  |
2. Drawing | .718 | NP | 11 (5.9%) | 8 (4.1%) | 1.02 | 11 (5.0%) | 17 (8.3%) | 2.14 | 19 (4.9%) | 28 (6.6%) | 1.11 |
 |  | RH | 161 (86.1%) | 176 (89.3%) |  | 193 (87.7%) | 175 (85.8%) |  | 337 (87.8%) | 368 (86.8%) |  |
 |  | LH | 16 (8.6%) | 20 (10.2%) |  | 30 (13.6%) | 13 (6.4%) |  | 36 (9.4%) | 43 (10.1%) |  |
3. Throwing | .427 | NP | 65 (34.8%) | 69 (35.0%) | 0.32 | 99 (45.0%) | 83 (40.7%) | 8.99* | 134 (34.9%) | 182 (42.9%) | 6.49* |
 |  | RH | 106 (56.7%) | 108 (54.8%) |  | 91 (41.4%) | 108 (52.9%) |  | 214 (55.7%) | 199 (46.9%) |  |
 |  | LH | 16 (8.6%) | 12 (6.1%) |  | 23 (10.5%) | 19 (9.3%) |  | 28 (7.3%) | 42 (9.9%) |  |
4. Holding Scissors | .659 | NP | 25 (13.4%) | 18 (9.1%) | 2.86 | 43 (19.5%) | 20 (9.8%) | 8.57* | 43 (11.2%) | 63 (14.9%) | 4.66 |
 |  | RH | 146 (78.1%) | 167 (84.8%) |  | 154 (70.0%) | 165 (80.9%) |  | 313 (81.5%) | 319 (75.2%) |  |
 |  | LH | 16 (8.6%) | 12 (6.1%) |  | 26 (11.8%) | 12 (5.9%) |  | 28 (7.3%) | 38 (9.0%) |  |
5. Brushing Teeth | .585 | NP | 44 (23.5%) | 49 (24.9%) | 0.89 | 57 (25.9%) | 47 (23.0%) | 5.75 | 93 (24.2%) | 104 (24.5%) | 0.81 |
 |  | RH | 127 (67.9%) | 136 (69.0%) |  | 137 (62.3%) | 145 (71.1%) |  | 263 (68.5%) | 282 (66.5%) |  |
 |  | LH | 11 (5.9%) | 14 (7.1%) |  | 20 (9.1%) | 14 (6.9%) |  | 25 (6.5%) | 34 (8.0%) |  |
6. Chopsticks | .689 | NP | 8 (4.3%) | 2 (1.0%) | 4.19 | 9 (4.1%) | 8 (3.9%) | 0.73 | 10 (2.6%) | 17 (4.0%) | 2.01 |
 |  | RH | 168 (89.8%) | 181 (91.9%) |  | 191 (86.8%) | 182 (89.2%) |  | 349 (90.9%) | 373 (88.0%) |  |
 |  | LH | 15 (8.4%) | 17 (9.0%) |  | 20 (9.1%) | 12 (5.9%) |  | 32 (8.7%) | 32 (7.5%) |  |
7. Spoon | .559 | NP | 41 (23.0%) | 34 (18.1%) | 1.38 | 57 (25.9%) | 66 (32.4%) | 3.13 | 75 (20.5%) | 123 (29.0%) | 7.61* |
 |  | RH | 122 (68.5%) | 137 (72.9%) |  | 143 (65.0%) | 126 (61.8%) |  | 259 (70.8%) | 269 (63.4%) |  |
 |  | LH | 17 (9.6%) | 18 (9.6%) |  | 26 (11.9%) | 32 (15.8%) | 4.53 | 35 (9.6%) | 58 (13.8%) |  |
8. Knife without fork | .520 | NP | 24 (13.6%) | 14 (8.0%) | 3.02 | 45 (20.5%) | 27 (13.4%) | Â | 39 (10.7%) | 72 (17.1%) | 11.57** |
 |  | RH | 136 (76.8%) | 155 (82.4%) |  | 148 (67.6%) | 143 (70.8%) |  | 291 (79.7%) | 291 (69.1%) |  |
 |  | LH | 30 (16.9%) | 26 (13.9%) |  | 40 (18.2%) | 30 (14.7%) |  | 56 (15.3%) | 70 (16.5%) |  |
9. Broom | .362 | NP | 49 (27.5%) | 42 (22.5%) | 2.44 | 61 (27.7%) | 51 (25.0%) | 1.79 | 91 (24.9%) | 112 (26.4%) | 0.57 |
(Upper hand) | Â | RH | 99 (55.6%) | 119 (63.6%) | Â | 119 (54.1%) | 123 (60.3%) | Â | 218 (59.7%) | 242 (57.1%) | Â |
 |  | LR | 11 (6.2%) | 20 (10.7%) |  | 20 (9.1%) | 21 (10.3%) |  | 31 (8.5%) | 41 (9.7%) |  |
10. Opening a box lid | .410 | NP | 78 (43.8%) | 69 (36.9%) | 3.38 | 116 (52.7%) | 95 (46.6%) | 1.61 | 147 (40.3%) | 211 (49.8%) | 9.10* |
 |  | RH | 89 (50.0%) | 98 (52.4%) |  | 84 (38.2%) | 88 (43.1%) |  | 187 (51.2%) | 172 (40.6%) |  |