INS and nutritional deficiency disease: Thrifty-genotype, thrifty-phenotype, and fetal insulin hypothesis: Thrifty-genotype and fetal insulin hypothesis state that multi-generational malnutrition has led to in-utero programming such that neonates of SA ethnicity are well adapted to an environment that is nutritionally limited but are more likely to become unhealthy in a nutritionally rich environment as they tend to accumulate more fat.