December 01, 2015

Attachment, Trauma, and Genetic Heritage Play Roles in Adopted Children’s School Success

Claire Chiamulera

The views expressed herein have not been approved by the House of Delegates or the Board of Governors of the American Bar Association, and accordingly, should not be construed as representing the policy of the American Bar Association.

A new study of children adopted into two-parent homes with well-educated, affluent parents uncovered some surprising results: troubling behaviors at school, less interest in learning tasks, and lower academic performance in reading and math. The reasons? Disrupted early attachments, lasting effects of early childhood trauma, and genetic heritage play a role, according to researcher Nicholas Zill in his research brief The Paradox of Adoption.

Zill, a researcher from the Institute for Family Studies, analyzed data from a longitudinal study of 19,000 kindergarten students conducted by the National Center for Education Statistics starting in 1998. The study included a large group involving adoptions of young children (160 children and families). All of the children were adopted early, some at birth. Assessments of the children’s school behaviors and academic performance were based on teachers’ reports and direct testing of the children. 

Children’s Behavior

Kindergarten and first-grade teachers rated the behavior of the children in the study sample on how well they got along with other children in group settings. Adopted children were reported to be more likely to get angry easily and argue and fight with other children than biological children. 

  • The average problem behavior rating for the adopted group was in the 64th percentile, compared to the 44th percentile for biological children (higher percentile rankings indicated more problem behaviors). 

  • Children in single-parent, step, and foster families were in the 58th percentile.

  • The rating remained high after adjusting for differences across groups in average child age, parent education level, and racial/ethnic gender composition.

Approach to Learning Tasks

Teachers rated adopted children on how well they paid attention in class, their eagerness to learn new things, and how they handled challenging learning tasks—factors known to predict later academic success. Adopted children were rated lower in these approaches than children raised by birth parents. 

  • The adopted children in kindergarten rated in the 45th percentile compared to the 57th percentile for children raised by birth parents (higher percentile rankings indicated a more positive approach to learning). The learning approach rating for children in single parent, step and foster homes was in the 43rd percentile.

  • The ratings were similar among adopted children in first grade (44th percentile) compared to biological children (56th percentile) and children in single, step, or foster families (42nd percentile).

  • The ratings of adopted children in kindergarten and first grade remained low after adjusting for age, sex, parent education, and ethnic differences.


Adopted children entering kindergarten were assessed on their pre-reading skills, including letter recognition, associating sounds with letters, and identifying simple words. 

  • The adopted children performed pre-reading tasks fairly well , ranking in the 53rd percentile, not far from children raised by birth parents (55th percentile). Children in single, step and foster families performed significantly lower (38th percentile). 

  • When adjusted for differences across groups in sex, parent education, and racial/ethnic composition, the ratings for the adopted group dropped significantly (44 percentile) while they rose for the children in single, step or foster families (45th percentile). 

  • The pattern continued for children in first grade. Tests of reading and word comprehension revealed children raised by birth parents ranked in the 56th percentile, with adopted children in the 49th percentile, and children in other families in the 41st percentile. Adjusting for demographic differences revealed similar findings.

Math Skills

Adopted children were tested on their pre-math skills in kindergarten (counting, recognizing numbers, understanding more, less and greater relationships). 

  • The adopted children rated fairly well --in the 50th percentile -- compared to the 59th percentile for children raised by birth parents and the 41st percentile for children in other family types. 

  • Adjusting for demographic differences resulted in a significant drop in the rating for adopted children to the 39th percentile, while children raised by birth parents were in the 52nd percentile and children in other family types rose to the 47th percentile.
  • Adopted children were also tested in the first grade on their grade-level math skills, rating poorly compared to children raised by birth parents and not far ahead children in other family types. 

  • The adopted children rated in the 40th percentile, not much ahead of the children in other family types in the 38th percentile and far behind children raised by birth parents in the 56th percentile. 

  • Adjustments for demographic differences between groups deepened the disparity, pushing their ranking down to the 32nd percentile compared to the 46th percentile for children in other family types, and the 52nd percentile for children raised by birth parents.

Bottom Line

Despite the high level of resources and plentiful nurturing adoptive parents bring to children, the study uncovered more problem behaviors in school and lower academic performance among these children in the early years . Zill offered three possible explanations: 

Disrupted attachments/lacking bonds affect behavior and take time to overcome. Disrupted attachments or a lack of a stable secure bond in early childhood before adoption can cause distress for children. They may express negative feelings and act out towards others. This distress can take time to resolve and may not be quickly transformed by a positive new home environment.

Early childhood trauma has lasting effects. Children who are maltreated or experience traumatic stress early in life can have long-term emotional scars. Severe or long-lasting effects of trauma can compromise a child’s development. A supportive adoptive family may only be able to partly reduce these effects.

Genetic heritage may limit learning. A child’s genetic predisposition to learning and educational achievement may limit their educational accomplishments. High levels of intellectual stimulation and resources provided by adoptive parents may never overcome the child’s genetic limitations.

Claire Chiamulera, CLP Editor

Nicholas Zill’s research brief, The Paradox of Adoption, is online: