Birth order effects on dermatoglyphs on fingers, palms, toes, and soles

Coefficients of correlation of 47 dermatoglyphic traits with birth order vary widely in a sample of 145 sibships of a Bengali speaking population. In general, ridge-counts and pattern intensities tend to decrease with birth order. Linear effects of birth order are, however, significant in samples of two sexes only for ridge-counts on the ab regions of palms and on toes, and in males only for triradial number on toes, D-line exit, hallucal ridge-count and triradial number on soles, and ridge-count on index fingers. Their relative intensities do not follow the order of appearance or of heritabilites of the traits. The maximal atd angle, which has a negligible correlation with birth order, shows no consistent trend of a linear or non-linear change with birth order in the two sexes even within sibships.