Children killed by genetic parents versus stepparents

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.