Table 1.

Demographics

	MZ	DZ	SIB
n individuals (MRI/IQ)	49/213	65/285	34/190
Sex, M/F (MRI)	34/15	33/32	19/15
Sex, M/F (IQ)	98/115	117/168	91/99
Hand, R/L, A (MRI)	41/8	54/11	29/5
Hand, R/L, A (IQ)	183/30	251/34	175/15
Age, years (MRI)	28.3 (3.6)	29.2 (8.7)	29.6 (4.8)
Age, years (VIQ, PIQ)	37.7 (36.6)	36.6 (13.3)	36.7 (13.2)
VIQ (% correct)	63.3 (13.3)	64.9 (12.2)	65.4 (13.3)
PIQ (% correct)	76.0 (12.8)	75.0 (14.0)	75.6 (13.2)

Values are shown as mean (SD). M, Male; F, female; R, right; L, left; A, ambidexter; SIB, singleton siblings of twin pairs.