Consanguineous marriage is a common and preferable custom of marriage among Afghans. Consanguineous marriage may cause transfer of two recessive defective alleles, one from the mother and the other from the father, to offsprings; which may cause appearance of congenital anomalies. Four generation of an Afghan family, residing in Afghanistan, and in which consanguineous and non-consanguineous marriages are practiced, were studied in this article. Out of 14 marriages, 7 were consanguineous and 7 non-consanguineous. Out of the offsprings of consanguineous marriages 52.3% presented congenital anomalies while among the generations of non-consanguineous parent no considerable congenital anomaly was observed.