Final answer:
DNA methylation is the process of adding a methyl group to a cytosine base in DNA, leading to possible gene silencing and affecting gene expression across generations.
Step-by-step explanation:
DNA methylation consists of the attachment of a methyl group onto a cytosine base in DNA. This epigenetic modification often leads to gene silencing and is a process that can suppress transcription. Moreover, the methylation patterns established can be inherited as cells divide and might be passed on from parents to offspring, influencing gene expression for generations.
DNA methylation primarily occurs within regions known as CpG islands which are found in the promoter regions of genes. The addition of a methyl group to the cytosine within these CpG dinucleotide pairs changes the interaction of DNA with various proteins, affecting the gene's transcriptional activity.