Building resources in the context of socioeconomic disadvantage: lessons from research for social policies

Abstract

Children are born with a biologically endowed potential, but what is made of this potential is the workings of their lifetime experiences with their environments. Human potential development refers to the development of competence to an optimal level, given the biological potential. It usually refers to a pattern of effective adaptation to environmental demands to reach reasonable success at developmental tasks expected of a person of a given age and gender in a society. It involves some comparison with established standards of performance, even if implicit. It also implies development vis-à-vis the biological potential. An issue dealt with in this chapter is that the given potential may or may not unfold to the same extent in individuals in widely different sociocultural contexts.

A widely accepted view stressing the priority of biological factors is the genotype-phenotype theory, proposed by Scarr (1992), which holds that each individual picks and chooses from a range of environments those that fit best his/her genetic potential/orientations. The theory thus claims that genetic endowment creates the environments individuals choose for themselves. When the global variability in environments is taken into consideration, however, the rather limited range of the theory's applicability becomes apparent. It assumes that people have equal opportunity or options to choose from and that there are options to choose from, yet a great many people in the world are not in a position to choose much at all. Environmental opportunities vary greatly, and particularly in deprived environments the genetic human potential may not get realized. Thus heritability for intelligence, for example, would be expected to be lower in deprived conditions than what is estimated for general populations. In other words, it may be higher in an adequate or ‘normal’ environment than in an impoverished one because the former provides the resources for the biological potential to be realized. Indeed, ample empirical evidence supports the nonlinear relationship with socioeconomic status (SES) of the proportions of intelligence quotient (IQ) variance attributable to heredity and environment. Thus, using data from the National Collaborative Perinatal Project with twins, Turkheimer, Andreana, Waldron, D'Onofrio, and Gottesman (2003) showed that 60% of the variance in IQ is accounted for by the shared environment and that the contribution of genes is close to zero in deprived homes, whereas the opposite is the case in affluent families. Other research corroborates in showing that heritability increases and effects of shared environment decrease as parental education increases (Rowe, Jacobson, & van den Oord, 1999; Thompson, Tiu, & Detterman, 1999).

Yet in most twin studies the lowest socioeconomic levels are underrepresented. This is also the case in adoption studies, as poor families are usually unable to adopt (Stoolmiller, 1999). This sampling bias results in doubtful external validity of the genetic estimates made from these studies for the entire socioeconomic spectrum, even in the United States, let alone globally (Neisser et al., 1996).