Differences in sensitivity to metabolic hormones and adipokines, such as leptin and insulin, may underlie some of the sex differences in the prevalence of type 2 diabetes and obesity, and interestingly, these hormones and adipokines are often altered by the nutritional environment of early life (Dearden et al., 2018). The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.