"Extrapolating from available data, the results indicated a considerably greater risk represented by stepfathers than by genetic fathers. At least five times as many children live with genetic fathers, while the raw frequencies of filicide were roughly equal in the two groups." (Harris et al. 2007). Research like this and studies such as Sarkadi et al. (2008)s', who end their abstract with"Conclusions: There is evidence to support the positive influence of father engagement on offspring social, behavioural and psychological outcomes. Although the literature only provides sufficient basis for engagement (direct interaction with the child) as the specific form of ‘effective’ father involvement, there is enough support to urge both professionals and policy makers to improve circumstances for involved fathering." , should be used by law makers to adjust the current system of family law in the UK.
Three studies investigating the risk stepparents pose to children:
Harris et al. (2008) Children killed by genetic parents versus stepparents. Evolution and Human Behavior, 28: 85-90
Despite many empirical studies of children killed by parents, there has been little theoretical progress. An examination of 378 cases in a national register revealed that circumstances differed for genetic parents versus stepparents. Infants were at greatest risk of filicide, especially by genetic mothers. Genetic mothers who killed offspring, especially older children, disproportionately had a mental illness and received relatively short sentences, if convicted. Filicides by genetic fathers were disproportionately accompanied by marital discord, suicide, and uxoricide. Filicides by stepparents were disproportionately common and likely to involve ongoing abuse and death by beating. Moreover, if parents also had genetic offspring, their stepchildren were at increased risk of ongoing abuse and neglect prior to death. Poor child health appeared to increase the risk of filicide by genetic mothers, especially as remaining opportunities for childbearing diminished. Although each finding might be consistent with existing lay accounts of filicide (depression, socioeconomic stress, etc.), together, they yielded a pattern uniquely consistent with selectionist accounts based mainly on parental investment theory.
Daly & Wilson (1988) Evolutionary social psychology and family homicide. Science, 242: 519-524
Homicide is an extreme manifestation of interpersonal conflict with minimal reporting bias and can thus be used as a conflict "assay." Evolutionary models of social motives predict that genetic relationship will be associated with mitigation of conflict, and various analyses of homicide data support this prediction. Most "family" homicides are spousal homicides, fueled by male sexual proprietariness. In the case of parent-offspring conflict, an evolutionary model predicts variations in the risk of violence as a function of the ages, sexes, and other characteristics of protagonists, and these predictions are upheld in tests with data on infanticides, parricides, and filicides.
Temrin et al (2004) Are stepchildren over–represented as victims of lethal parental violence in Sweden? Proc R Soc, 271: S124-S126
Evolutionary psychologists have suggested that stepchildren should be over–represented as victims of lethal parental violence compared with children living with their two genetic parents, because of relatively more lapses in parental solicitude among step–parents. In our study, using data over a period of 35 years in Sweden (1965–1999), there was no overall over–representation of stepchildren as victims. For very young stepchildren there was a tendency for over–representation. In families with both stepchildren and children genetically related to the offender, genetic children tended to be more likely to be victims.
Study showing the importance of fathers in the development of children:
Sarkadi et al. (2008) Fathers' involvement and children's developmental outcomes: a systematic review of longitudinal studies. Acta Paediatria, 97:153-158
Objective: This systematic review aims to describe longitudinal evidence on the effects of father involvement on children's developmental outcomes.
Methods: Father involvement was conceptualized as accessibility (cohabitation), engagement, responsibility or other complex measures of involvement. Both biological fathers and father figures were included. We searched all major databases from the first dates. Data on father involvement had to be generated at least 1 year before measuring offspring outcomes.
Results: N = 24 publications were included in the overview: 22 of these described positive effects of father involvement, whereof 16 studies had controlled for SES and 11 concerned the study population as a whole [five socio-economic status (SES)-controlled]. There is certain evidence that cohabitation with the mother and her male partner is associated with less externalising behavioural problems. Active and regular engagement with the child predicts a range of positive outcomes, although no specific form of engagement has been shown to yield better outcomes than another. Father engagement seems to have differential effects on desirable outcomes by reducing the frequency of behavioural problems in boys and psychological problems in young women, and enhancing cognitive development, while decreasing delinquency and economic disadvantage in low SES families.
Conclusions: There is evidence to support the positive influence of father engagement on offspring social, behavioural and psychological outcomes. Although the literature only provides sufficient basis for engagement (direct interaction with the child) as the specific form of ‘effective’ father involvement, there is enough support to urge both professionals and policy makers to improve circumstances for involved fathering.