Possible mechanisms by which insults in early life retain long-lasting effects are still poorly understood. One possibility is that permanent changes occur in an organ system due to sub-optimal conditions during a critical period of development, such as reduction in cell number (e.g. permanent reduction in beta cell mass in the pancreas or nephrons in the kidneys), or altered structure (e.g. thickness of blood vessels), or functioning (e.g. re-setting of the hypothalamic-pituitary-adrenal axis). The relatively new science of epigenetics offers a plausible explanation. Programming effects may act through ‘epigenetic’ mechanisms that alter expression of genes without altering the base sequence (i.e. change in phenotype independent of change in genotype). The expression of genes is thought to be regulated by three main processes: 1) methylation or de-methylation in gene promoter regions, 2) acetylation of histones, and 3) modification of micro RNAs. We are carrying out epigenetic studies in partnership with Giriraj Chandak and his team at the CSIR-Centre for Cellular and Molecular Biology in Hyderabad, India.