Published online by Cambridge University Press: 15 September 2014
The introduction of standardised methods for describing that characteristic of social behaviour denoted by the word intelligent is of comparatively recent date. Therefore it is not feasible to undertake a study of the intellectual resemblance of relatives along the ancestral line. In two classes of collateral relatives, however, such resemblance can be made the subject of inquiry. These are (a) members of the same fraternity— twins or ordinary sibs—and (b) first cousins. This investigation, which was prompted by a previous inquiry into the intellectual resemblance of twins carried out in the Department of Social Biology, is confined to a study of ordinary sibs and first cousins. Though resemblance between both sibs and first cousins has already been investigated, there are in each case special reasons which justify further inquiry.