Vol. 1, No. 3 , 1995, Page 6 
|
Vol. 1, No. 3 , 1995, Page 6 |
A recent study by Dutch researchers reports substantial genetic influences on
delinquent and aggressive behavior.
In a unique study design, Edwin J.C.G. van den Oord et al. compared 221 pairs of biologically unrelated siblings in adoptive families to 111 pairs of biologically related siblings who had been kept together when adopted. "Adopted children are usually compared with controls who are raised by their biological parents," the researchers say, "while in our study both groups [were] raised by adoptive parents." A group of children with no siblings was included as a control.
The researchers report that among their subjects, "genetic influences accounted for 70% of the variance of aggressive behavior," while a heritability of 39% was found for delinquency. "For attention problems," they say, "genetic influences accounted for 47% of the variance, whereas shared environmental influences were very small."
Unlike several other researchers, however, van den Oord et al. found only weak genetic influences on anxiety, depression, and withdrawal.
"A study of problem behaviors in 10- to 15-year-old biologically related and unrelated international adoptees," Edwin J.C.G. van den Oord, Dorret I. Boomsma, and Frank C. Verhulst, Behavior Genetics, Vol. 24, No. 3, 1994. Address: Edwin J.C.G. van den Oord, Czar Peterstraat 35G, 1018 NX Amsterdam, The Netherlands.