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Conclusions 469female offspring. This altered parenting behavior can then influence subsequentgenerations of offspring producing intergenerational effects on stress responsesand parenting behavior. His work using cross-fostering designs indicates that theseeffects can be reversed when a nurturing mother raises the offspring of a nonnurturantmother. His work also suggests that stressful environments can unleashnonnurturant patterns of parenting and that these environments influence geneticexpressions that control behavior into adolescence and adulthood. Although thispattern of gene expression may be adaptive for offspring born into high stressenvironments, it is likely to predispose offspring to later affective disorders andhyperreactivity to stressors (see also Teicher et al., 2003).Meaney’s research with an animal model may not translate completely to humans;however, the parallels are quite striking. Child abuse appears to have a strong intergenerationalpattern that has been subject to either a genetic or modeling interpretation(Buchanan, 1996; Thompson, 1995). In addition, chronic poverty and stress arestrong predictors of abusive and neglectful parenting (Repetti, Taylor, & Seeman,2002). Meaney’s research suggests that chronic stress may unleash genetic effects inoffspring mediated by nonnurturing parental behavior. He terms this a “nongenomic”effect because the neglectful behavior of the parent initiates it, and a nurturant parentcan reverse it. Virtually the same effects of maternal behavior have been observed inSuomi’s (1997) studies of rhesus monkeys who share many more social and behavioralcharacteristics with humans than rats. Suomi’s research has also examined theeffects of nonnurturant rearing on male development. His studies suggest that malesraised by nonnurturant females are more likely to exhibit impulsive and aggressivebehavior than males raised by normal or highly nurturant females.Even if the animal models developed by Meaney and Suomi do not translatecompletely to humans, their outcomes explain the beneficial effects that have beenobserved for interventions designed to provide support during the pre- and postnatalperiod to mothers in high-risk (low-SES, single-parent) households (Olds,Henderson, Cole, Eckenrode, Kitzman, Luckey, et al., 1998). This home visitationprogram by public health nurses has been found to reduce maladaptive andabusive parenting, decrease the incidence of externalizing disorders in adolescence,and increase the adaptive functioning of mothers well beyond the early years ofchildbearing (Izzo et al., 2005). Gunnar (chapter 6) also finds evidence for thereversibility of early unresponsive parenting in human infants. Research she citesthat examines the effects of nurturant foster care on previously institutionalizedchildren suggests that HPA functioning can return to more normal levels of functioningif the intervention occurs during the preschool years. Research by Nelsonand colleagues (chapter 9), with more seriously neglected children left in Romanianinstitutions, suggests that even such severely disrupted development can bepartially reversed by appropriate foster care placement.The evidence now accumulating from research with lower animals suggests thatparenting interventions have the ability to prevent genetic effects that predispose