Table 5.
Mean and Standard Deviations of Psychological Femininity in Female Twins From Same- Versus Opposite-Sex Pairs, for Entire Sample and the Reproductive Fitness (Over 50) Subsample
| Same-sex pair | Opposite sex pair | |||||||
|---|---|---|---|---|---|---|---|---|
| Mean | SD | N individuals | Mean | SD | N individuals | χ12 | p | |
| Australian | ||||||||
| Entire sample | 13.62 | 3.14 | 3131 | 13.88 | 3.26 | 688 | .01 | .98 |
| over 50 | 13.25 | 3.06 | 299 | 13.93 | 3.06 | 143 | 4.51 | .03 |
| Dutch | ||||||||
| Entire sample | 27.76 | 4.37 | 860 | 27.41 | 4.40 | 557 | 2.00 | .16 |
| over 50 | 27.54 | 4.38 | 129 | 26.57 | 4.16 | 55 | 1.81 | .18 |
| US | ||||||||
| Entire sample | 11.46 | 3.17 | 6190 | 11.53 | 3.11 | 1341 | .50 | .48 |
| over 50 | 11.75 | 3.12 | 1455 | 11.81 | 3.08 | 668 | .17 | .68 |
Note: p = probability based on t test of the difference between means; d = effect size, the effect on femininity of having a female twin, in SD units.