Assessment of inbreeding depression on morphometric traits among North Indian population cohorts

Inbreeding is thought to affect the morphometric parameters leading to lower health status among the progeny. The present study was aimed to investigate the repercussions of inbreeding on anthropometric traits, namely height, weight and body mass index (BMI).

The survey was conducted in two North Indian cities and total 813 individuals were randomly recruited from inbred and outbred families. The morphometric parameters of the subjects were measured using standard methods, BMI was calculated and categorized into underweight, normal weight and overweight. Family pedigrees were drawn and degree of inbreeding in terms of the inbreeding coefficient (F) was calculated.

A significant decline in morphometric measures was observed among inbred individuals as compared to outbred ones. The mean differences (95% CI) were found significant for various inbred and first cousin categories as compared to outbred subjects (p < 0.05). We found the increased frequency of underweight individuals corresponding to the degree of inbreeding for different types of inbred categories (p = 2.086 × 10⁻⁹) and also for different subtypes of first cousin unions corresponding to their sex-linked inbreeding coefficients (p = 5.2 × 10⁻⁵). The regression slope and correlation coefficient revealed a fitness decline and depression in anthropometric measures (p < 0.05) with the increase in ‘F’ for all inbred groups and first cousin categories.

The present research confirms the adverse effects of inbreeding on morphometric parameters among inbred subjects. It has novelty in shedding light on the hitherto unreported differences in the consequences of inbreeding among different types of first cousin unions.