Table 1.

Descriptive statistics of the full- and half-sibling samples

Sibling sample	No. of individuals	Biological parent education, mean (SD)	Adoptive parent education, mean (SD)	IQ score, mean (SD)
Full-siblings
Reared	590	2.01 (1.0)		92.0 (14.1)
Adopted-away	453	2.01 (1.0)	2.64 (1.3)	96.9 (14.5)
Half-siblings
Reared	3,144	2.42 (1.1)		95.2 (14.4)
Adopted-away	2,400	2.36 (1.1)	2.70 (1.3)	98.4 (14.6)