Summary

The international literature as we have reviewed it suggests that, while genetics provides an important causal link from parents to child outcomes, the environment a child is raised in represents an equally important link. However, our conception of the environment that is relevant for this process has grown from an early focus on home environments to our present focus on broader environments such as neighborhoods, schools and broadly defined "community groups." While there is evidence that shared home environments do matter for outcomes measured early in life, the same evidence tends to suggest that such environments become less important as causal explanations for outcomes in adolescence and adulthood. Furthermore, even for outcome measures early in life, certain candidates for home environment factors are increasingly being ruled out as causal factors in explaining differences in many outcomes, factors like family income, differences in parenting styles and certain aspects of family structure. To the extent that they do matter, these factors seem to be more important for children commonly labeled as at-risk, with factors like divorce and single parenthood as well as supervised child care playing a potential role. Parental choices outside the home also have some impact, with choice of school and community potentially important. Parental involvement in schools tends to raise school quality somewhat, even if a great portion of this may be specific to the child whose parents are involved. There is also evidence for some within-class peer effects even if it is difficult to interpret precisely what this evidence means. Finally, while there seems to be increasing consensus around the premise that broader neighborhood effects related to residential, ethnic and cultural communities are important, we still know little about these effects and find them difficult to quantify.

One of the broad themes of the review is that much of the earlier literature was largely correlational in nature, and researchers were often too quick to conclude that observed correlations implied causal relationships. As more sophisticated statistical techniques to control for a variety of possible biases became available, more careful analysis began to suggest that many of these initial results were incorrect. With respect to home environments, the more sophisticated analysis led to a general finding of smaller causal effects in most cases. With respect to schools, some of the most recent evidence is more positive than what was reported from initial correlations, and for neighborhood effects the evidence remains unclear, even if some optimism currently exists that more definitive and larger findings will be facilitated by better data on relevant "neighborhood" groups. In terms of broad trends, we think it accurate to characterize the earlier correlational literature as more eager to find large effects and more willing to over-interpret correlations in the data. In contrast the more recent literature is typically more methodologically careful and more satisfied with modest results. The idea of a "big answer" to the question of why children turn out as they do is largely gone, and new efforts are increasingly aimed at finding smaller but more consistent and reliably estimated effects. We generally view this as progress, even if it has meant letting go of some easy but incorrect policy answers. We also think that the international literature has much to tell New Zealand researchers, and discuss some of these implications in detail. In particular, the international research can aid in the interpretation of current New Zealand specific findings as well as in fine-tuning research on especially unique aspects of New Zealand .