II.—N ature ‐N urture B alance S heets

S ummary .— Empirical studies have brought the nature‐nurture controversy no nearer to a generally agreed solution. Attempts to derive a nature‐nurture balance sheet from genetic theory fail to take into account the correlation between heredity and environment. Shuttleworth's widely quoted balance sheet rests on some doubtful assumptions. The only unequivocal evidence is derived from identical twins reared apart, but, in any case, any particular balance sheet can be neither final nor of general applicability since heredity and environment are in dynamic interaction. Test variance in groups whose education has been defective is likely to include an unusually large environmental contribution.