to other children, more behavior problems in early childhood when experiencing low-quality parenting36 or low-quality child care,37, 38 but also fewer problems and more social skills than other children when exposed to high-quality parenting or child care. Relatedly, Kochanska et al.39 observed that highly fearful 15-month-olds experiencing high levels of power-assertive paternal discipline were most likely to cheat in a game at 38 months, yet when cared for in a supportive manner, such negatively emotional, fearful and putatively vulnerable toddlers manifested the most rule-compatible conduct. Even more noteworthy than such longitudinal/correlational evidence is the clinical-trial finding of a parenting intervention designed to promote secure attachment of infant to mother showing that the principle beneficiaries of the documented experimental effect were highly negative and fearful infants.40 These findings pertaining to negatively emotional infants demonstrate not only that such putatively vulnerable children are more beneficially affected than other infants by some enriching rearing conditions but, in so doing, raise the prospect that this could be because they are carriers of short alleles on the serotonin transporter gene. Only when investigators evaluate interactions involving both the environment and genetics, and the environment and temperament will it be possible to determine whether the same
