The dubious history of the heredity environment controversy can be easily traced as far back as the start of the present century with at least some historical evidence placing the roots of this dispute in the time of John Locke.
This controversy has continued despite continual reiteration that the critical question is not how much of a trait is due to heredity and how much is due to environment, but rather how environment transact to influence development." (
Wachs , 1983, p. 386). This paper will focus on the nature/nurture controversy and the extent to which an individuals intellectual level is determined either by inborn intelligence or by environmental factors. The relative powers of nature …show more content…
This fact helps to illustrate that IQ is strongly influenced by both genetic and environmental factors.
Adoption studies are important for us to look at because they provide one of the few methods available for separating the effects of environment and heredity in intellectual development. When adopted children are more like their biological parents and siblings, we see the influence of heredity; when they resemble their adoptive families more, we see the influence of environment. The Texas Adoption Project (Horn, 1983) conducted intelligence tests from parents and children in 300 adoptive families and compared them with similar measurers available for the biological mothers of the same adopted children. The results of this study supported the hypotheses that genetic variability is an important influence in the development of individual differences for intelligence. The study also concluded that adopted children resemble their biological mothers more than they resemble the adoptive parents who reared them from birth. In an extensive study dealing with the mental growth of foster children after they had lived in their new homes found that on the whole, they improved their mental status, the