J. A. H. Waterhouse, Lecturer in Human Genetics at the University of Birmingham, explains how the study of twins helps to throw light on the problems of heredity.
The programme is introduced by Dr. J. Bronowski, who also reports on replies received from viewers on the previous programme 'The Common Cold'.
Viewers who are twins are invited to submit certain details about themselves to 'Twin Sister, Twin Brother,' BBC Television Service, [address removed]
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