The Mendelian theory of the segregation of unit characters, though it is far, as yet, from being completely demonstrated, offers a simple explanation of some striking features of inheritance. In particular, Mr. E. C. Snow has recently shown that the gametic correlations for collaterals deducible from the Mendelian hypothesis are in close agreement with the actually observed somatic correlations for man and certain other animals; or, in other words, that a Mendelian theory of segregation without dominance gives values for collateral resemblance not greatly differing from those found from observation. It seems, therefore, possible that the same theory will throw some light on the problem of inbreeding, or, at any rate, will indicate to what points, on which precise data are at present lacking, statistical enquiry should be directed. Without these data the Mendelian theory cannot be corroborated or negatived by the methods of the present paper. So far as they go, however, the statistics at present obtainable with regard to consanguinity in the parentage of albinos and deaf mutes are in approximate agreement with the calculated results, although the accuracy of the figures is too uncertain for the application of anything more than a rough criterion.
Inbreeding in a stable simple Mendelian population with special reference to cousin marriage
