Table B1.

BDNF

Dependent Variable: High School IQ
	(1)	(2)	(3)
Panel A: BDNF = Categorical
BDNF	0.0045 (0.8455)	0.0708 (0.8282)	1.4912 (1.2867)
Standardized Birth Weight	2.0633 (1.6560)	1.3300 (1.5164)	2.7466 (2.0975)
G × E	−0.3912 (0.9269)	0.0604 (0.8776)	−0.8219 (1.1457)
Controls
Demographic and Family SES	Y	Y	Y
Sibling Fixed Effects	N	N	Y
Estimation
Weighting by Prob. of Being in Sib Sample	N	Y	N
N	938	938	938
R Sqr.	0.1314	0.1274	0.6964
Panel B: BDNF = Indicator for at Least One Plastic Allele
BDNF	−2.7718 (2.1192)	−3.2794* (1.9548)	−1.2093 (2.4292)
Standardized Birth Weight	4.9296* (2.8294)	4.9697* (2.5840)	1.3985 (3.5031)
G × E	−3.5965 (2.8408)	−3.6098 (2.6162)	0.0130 (3.5019)
Controls
Demographic and Family SES	Y	Y	Y
Sibling Fixed Effects	N	N	Y
Estimation
Weighting by Prob. of Being in Sib Sample	N	Y	N
N	938	938	938
R Sqr.	0.1336	0.1300	0.6952
Panel C: BDNF = Indicator for Two Plastic Alleles
BDNF	0.4237 (1.0152)	0.5419 (1.0186)	2.3319 (1.5569)
Standardized Birth Weight	1.4989* (0.8716)	1.1763 (0.8106)	2.3262* (1.1860)
G × E	−0.1269 (1.0035)	0.3736 (0.9824)	−1.3270 (1.3111)
Controls
Demographic and Family SES	Y	Y	Y
Sibling Fixed Effects	N	N	Y
Estimation
Weighting by Prob. of Being in Sib Sample	N	Y	N
N	938	938	938
R Sqr.	0.1314	0.1279	0.6974

Notes: (i) This table performs our base estimation (Table 4) while restricting our neuroplasticity measure solely to the SNP of BDNF. Panel A uses the count of plastic alleles (i.e., 0, 1, 2); Panel B uses an indicator for individuals who have at least one plastic variant; and Panel C uses an indicator for individuals containing two plastic variants. (ii) For our base sibling sample, 4.69% (N=44) do not carry a plastic variant of BDNF, 29.64% (N=278) carry one plastic variant, and 65.67% (N=616) carry two plastic variants.