Genetic basis of hair medulla by twin study.
Data on the incidence of medulla of human head hair based on 9,600 strands examined from 48 pairs of zygosity--determined German twins were quantified as medullary ratio and subjected to variance analysis to give information about genetic significance of the character concerned. The results of F test and heritability estimate yielded significant values indicating the presence of a strong genetic component of variability in the incidence of medulla of human head hair. Sex influence upon the character is found to be absent.
D005260:Female; D005826:Genetics, Medical; D006197:Hair / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D011247:Pregnancy; D012737:Sex Factors; D014427:Twins