Stable care helps adopted children overcome harmful consequences

A supportive upbringing is crucial for an adoptive child’s development, concludes Leiden PhD candidate Christie Schoenmaker. Malnourished adopted children initially have a lower IQ score, but malnutrition does not have any consequences for their occupational level later on.

Adopted children tracked for 20 years

Children adopted internationally have often had a difficult start. They are frequently malnourished and could not depend on the support of their carers. The children experience a drastic change if they are taken in by a stable adoptive family. The children, originally come from Sri Lanka, South Korea and Colombia, who were the subject of the Leiden Longitudinal Adoption Study were placed in Dutch families before they were 6 months old. In this unique study, adoptive children were followed for more than 20 years during which period they underwent intensive observations and assessments. For all the children, their initial state of health was known, including whether they had suffered from malnutrition.

The influence of upbringing

The big question is how children subsequently develop in their new environment. Among other things, Schoenmaker studied the consequences of malnutrition for the later intellectual development of adopted children and whether this effect is reversible. She also looked into the influence that being brought up in an adoptive family had on adopted children’s development. These children’s basic trust may be damaged. How does this trust develop over time, and what role do adoptive parents play in that development? Schoenmaker: ‘Because the adoptive parents and the children are not genetically related, you can separate the influence that upbringing has on the child’s development from genetic influences that could cause similarity between the parent and the child.’

Social skills

In this longitudinal study, adopted children took intelligence tests at various ages, and their school trajectory and career were also tracked. Schoenmaker ascertains that early malnutrition correlated with the adopted child having a lower IQ at 7 years of age and (to a lesser degree) at 23. ‘The good news is that early malnutrition plays no role in the adopted child’s occupational level. Adopted children with early malnutrition have just as good a social position as those without early malnutrition. So, other factors are also important in getting a good job, such as social skills that adopted children learn from their adoptive family.’


The Leiden researchers observed supportive parental behaviour (sensitivity) and the quality of the parent–child relationship (attachment). Then the adopted children were seen during assessments at 7, 14 and 23 years of age, in which parental sensitivity and attachment were also looked at. What these showed was that the more sensitive the adoptive parent is, the better the attachment relationship. What was striking is that the adoptive parent’s sensitivity during infancy and the elementary school years also predicted the adopted child’s degree of attachment at the age of 23.

Positive intervention

Schoenmaker concludes: ‘The results show that an adverse start is not decisive for an adopted child’s development. Stable care on the part of the adoptive parents can help these children overcome harmful consequences. Adoption is shown to be a positive intervention, not only in the short term, but in the long term as well. Adoption also confirms the premise that the family environment is very important in a child’s development.’

PhD defence C. Schoenmaker 16 April - From Infancy to Young Adulthood: The Leiden Longitudinal Adoption Study

(23 April 2014)

See also

Studying in Leiden



Last Modified: 23-04-2014