Final answer:
DNA methylation is a key player in imprinting, where it leads to gene silencing based on parental origin, and environmental factors can influence these methylation patterns, affecting gene expression in offspring.
Step-by-step explanation:
DNA methylation plays a critical role in the process of imprinting, a biological mechanism that involves the epigenetic silencing of specific genes, depending on whether they are inherited from the mother or the father. During gamete formation, specific genes are silenced through methylation, occurring in CpG islands within the promoter regions of genes. This silencing is then passed on to the offspring, resulting in the gene being 'imprinted' and thus expressed in a parent-of-origin-specific manner. Environmental factors such as diet can affect DNA methylation patterns, potentially influencing gene expression and leading to heritable epigenetic changes. Additionally, DNA methyltransferases, which add methyl groups to DNA, are attracted to chromatin regions with particular histone modifications, and highly methylated regions with deacetylated histones are tightly coiled and transcriptionally inactive.