Citation

Freedman DG, Keller B. Science 1963; 140(3563): 196-198.

Copyright

(Copyright © 1963, American Association for the Advancement of Science)

DOI

unavailable

PMID

13959419

Abstract

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 N(1) of 11 fraternal and N(2) of 9 identical pairs. Within-pair differences were significantly greater within fraternal pairs on all tests and rating scales.

Language: en