Manning J T, Denman J
Department of Environmental and Evolutionary Biology, University of Liverpool, United Kingdom.
J Comp Psychol. 1994 Sep;108(3):262-5. doi: 10.1037/0735-7036.108.3.262.
Women (Homo sapiens) tend to cradle infants on the left side of the body. We report the results of a survey of family photograph albums. We found that left-side cradling frequencies (LCFs) are higher in women than in men and that there are strong significant correlations between the LCFs of mothers and daughters, sisters, and maternal grandmothers and granddaughters. There may be a genetic influence on lateral cradling tendencies; women's left-side cradling preferences were found to be repeated with subsequent children. Heritability of women's LCF has an upper limit of 0.82, and the regression of daughters' mean LCF on mothers' LCF gives a heritability of 0.93 +/- 0.29. The data may be interpreted in two ways: There may be sex-limited genes (i.e., genes that express themselves only in women) for lateral cradling preferences, or women may learn cradling preferences from their mothers and other female relatives.
女性（智人）倾向于将婴儿抱在身体左侧。我们报告了一项对家庭相册的调查结果。我们发现，女性的左侧抱婴频率（LCF）高于男性，并且母亲与女儿、姐妹以及外祖母与外孙女之间的LCF存在很强的显著相关性。可能存在对横向抱婴倾向的遗传影响；研究发现，女性对左侧抱婴的偏好会在后续子女身上重复出现。女性LCF的遗传率上限为0.82，女儿平均LCF对母亲LCF的回归得出遗传率为0.93±0.29。这些数据可以有两种解释：可能存在决定横向抱婴偏好的性别限制基因（即仅在女性中表达的基因），或者女性可能从母亲和其他女性亲属那里习得抱婴偏好。
