Inbreeding Effects on Metrical Phenotypes Among North Indian Children

This study aimed to examine the effects of inbreeding on 12 quantitative phenotypes like body weight, height, sitting height, head circumference, head length, head breadth, chest circumference, verbal, performance and full scale intelligence quotients, systolic and diastolic blood pressures among North Indian Children. The sample consisted of 3,253 subjects (1,683 males and 1,570 females) including offspring of first cousins, first cousins once removed, second cousins, (inbred part of samples) and unrelated spouses (non-inbred part of samples) ranging in age from 6 to 14 years from the Aligarh district, Uttar Pradesh in North India. Samples were selected purposively to estimate the average inbreeding coefficients based on 3 ancestral generations and using Wright’s path method. The average inbreeding coefficient of the present inbred part of sample is 0.04609. The mean ages of males and females were almost equal for both inbred and non-inbred individuals. A significant reduction of means (p < 0.05) or inbreeding depression has been observed in inbred series for all anthropometric and psychometric traits for both the sexes. A significant elevation of mean with inbreeding is observed for systolic and diastolic blood pressure. The average inbreeding depression per 10% inbreeding appeared very high in verbal IQ ( 23), performance IQ ( 40), full scale IQ ( 28), systolic blood pressure ( 10) and diastolic blood pressure ( 12) among both sexes. On the whole, relatively greater amount of inbreeding effects are apparent among all measures of intelligence quotient and blood pressures compared to the anthropometric traits.The results of the present work have thrown light on the nature and mechanism of genetic effects of inbreeding on certain quantitative traits in human