Inheritance of Behavior in Infants

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Science  12 Apr 1963:
Vol. 140, Issue 3563, pp. 196-198
DOI: 10.1126/science.140.3563.196


Mental and motor abilities and personality development were studied in 20 pairs of infant twins of the same sex on a monthly basis in their first year, that is, before mutual imitation becomes a factor. Blood group determinations, made after the study was completed, revealed an N1 of 11 fraternal and N2 of 9 identical pairs. Within-pair differences were significantly greater within fraternal pairs on all tests and rating scales.