[Bi-allelic genetic markers and the determination of family relationships].

A very useful index for the validation of family relationship by means of genetic markers is the proportion of males in the population whose phenotype makes paternity of a child of known phenotype impossible: the proportion often indicates probability of exclusion of paternity. It may be proved in the case of biallelic mendelian systems that this probility of exclusion of paternity may be modified by close relationship between the mother and father of the child or between the real father of the child and the presumptive father.