RT Journal Article SR Electronic T1 The Impact of Family Composition on Educational Achievement JF Journal of Human Resources JO J Hum Resour FD University of Wisconsin Press SP 0915-7401R1 DO 10.3368/jhr.54.1.0915.7401R1 A1 Chen, Stacey H. A1 Chen, Yen-Chien A1 Liu, Jin-Tan YR 2017 UL http://jhr.uwpress.org/content/early/2017/07/05/jhr.54.1.0915.7401R1.abstract AB Parents preferring sons tend to go on having more children until a boy is born, and to concentrate investment in boys for a given number of children (sibsize). Thus, having a brother may affect a child's education in two ways: an indirect effect by keeping sibsize lower and a direct rivalry effect where sibsize remains constant. We estimate the direct and indirect effects of a next brother on the first child’s education conditional on potential sibsize. We address endogenous sibsize using twins. We find new evidence of sibling rivalry and gender bias that cannot be detected by conventional methods.