A study of Eastern European children adopted by American families showed that age at adoption affected their English language development. The study controlled for a number of other factors, including developmental delays and premature birth. The earlier the children were adopted the better was their language development; the later their adoption, the more they lagged and the more severe their language problems were.1) Those adopted within their first year had, within two years of their placement, attained command of the English language normal for their age. Older adoptees caught up more slowly. Those adopted still later experienced increasingly greater lags. For instance, those adopted at 25 to 30 months of age showed an eight to 10 month delay a year after being adopted.2)
Adopted children who experience abuse and neglect have poorer social adjustment and weaker outcomes than adopted children who were not abused or neglected.3) Though they achieve less in school, their IQ scores revealed no corresponding difference.4)
Adopted children exposed to drugs in utero, despite attaining good grades as frequently and doing as well in speech and language as non-exposed children, were more likely to repeat a grade or have learning disabilities that required enrollment in special classes.5)
Adopted children outperform their non-adopted siblings and birth peers in math, reading, and general academic capacity, as well as in adult qualifications later in life.6) Adoption has a positive impact on children’s cognitive development and competence, though adopted children tend to have a somewhat delayed school performance.7) However, adopted children never lag significantly behind the general population. Adopted boys do better than the general population on reading; this is primarily attributable to adoptive parental interest in their education.8) In 1981, according to the testimony given by Nicholas Zill, a vice-president at Westat, MD, before the House Ways and Means Subcommittee on Human Resources, only seven percent of children adopted in infancy repeated a grade, while 12 percent of children living with both biological parents repeated a grade.9)
However, many general studies show that when the academic performance of adopted and non-adopted children is compared, adoptees have lower grades and more learning difficulties.10) Teachers report that adoptees lag behind non-adopted children in academic attainment, originality, capacity to learn independently, participation at school, and productive peer engagement.11) Furthermore, adopted children are significantly more likely to require special treatment for learning disabilities than are non-adopted children.12)
A study by Sandra Scarr, then a professor of psychology at Yale University, and Richard Weinberg, then a professor of psychology at the University of Minnesota, found that, though adopted children’s IQs tend to correlate with their biological mothers’education levels, earlier placement leads to a higher IQ score. They found that, eventually, there are no differences between the IQ scores of adopted siblings and those of biological siblings reared together. Researchers who investigated the IQ differences among 400 brothers in Sweden discovered that the average adopted male sibling had an IQ score of 97 while those raised by their biological parents had an average IQ score of 92.13) Another study confirming the “earlier is better pattern” showed that later-adopted children are twice as likely as non-adopted children to have learning problems that necessitate special education.14)
Teacher reports in the aforementioned Swedish longitudinal study found that, at 11 years of age, adopted boys were more prone to behavior problems and adopted girls lagged behind their peers in math. At age 15, adopted boys and girls earned lower average grades than their classmates. Despite all this, at 18 years of age, military records show that adopted boys’ IQ scores matched those of their control group.16) Another study found that adoptees who are placed in their first twelve months perform in step with the general population at school, whereas those adopted after one year lag behind their peers.17)
A number of international studies showed that adoptees were referred for special education twice as often as non-adoptees. However, they also showed that adoptive parents were more informed about available services and more alert to potential problems than were non-adoptive parents, and were thus more likely to seek out such services and refer their children to them.18) Thus, the rate of special needs services likely reflects the higher level of care and concern repeatedly evidenced by adoptive parents.