If a child is exposed to a hypercaloric postnatal diet without adequate nutrition or without the ingestion of breast milk, altered levels of hormones or biomarkers which have undergone epigenetic alterations when facing an unfavorable environment, such as leptin, growth hormone (GH) or insulin-like growth factor 1 (IGF-1), may favor metabolic actions outside appropriate physiological patterns, inducing obesity or other metabolic disorders in the medium and long term [14]. The gene discussed is IGF1; the disease is obesity due to melanocortin 4 receptor deficiency.