Accessible Requires Authentication Published by De Gruyter January 19, 2010

IQ and Family Background: Are Associations Strong or Weak?

Anders Björklund, Karin Hederos Eriksson and Markus Jäntti

Abstract

For the purpose of understanding the underlying mechanisms behind intergenerational associations in income and education, recent studies have explored the intergenerational transmission of abilities. We use a large representative sample of Swedish men to examine both intergenerational and sibling correlations in IQ. Since siblings share both parental factors and neighbourhood influences, the sibling correlation is a broader measure of the importance of family background than the intergenerational correlation. We use IQ data from the Swedish military enlistment tests. The correlation in IQ between fathers (born 1951-1956) and sons (born 1966-1980) is estimated to 0.347. The corresponding estimate for brothers (born 1951-1968) is 0.473, suggesting that family background explains approximately 50% of a person's IQ. Estimating sibling correlations in IQ, we thus find that family background has a substantially larger impact on IQ than has been indicated by previous studies examining only intergenerational correlations in IQ.

Published Online: 2010-1-19

©2011 Walter de Gruyter GmbH & Co. KG, Berlin/Boston