Gender and birth order as determinants of parental behaviour

This study analyses the effect of gender and birth order of fifty-eight 3-month-old first- and laterborn boys and girls on parental treatment. Presence of parents, maternal primary care, and maternal and paternal facial exchange with the baby were assessed during videotaped observation sessions equivalent to a full day. The data reveal a sound birth rank effect, indicating that firstborns are preferred over laterborns in several respects: presence of mothers, presence of fathers, and father’s face-to-face behaviour when the mother is also present. With respect to gender differences, mothers prefer their daughters in terms of presence and primary care. Fathers prefer their sons in terms of presence. Unexpectedly, fathers prefer their daughters in terms of face-to-face exchange. The social context of fathers’ and mothers’ joint presence reveals the only interaction effect between gender and birth order with the preference of firstborn boys. The findings are related to previous research results as well as evolutionary considerations about parental investment.