Final answer:
Gene methylation, a reversible addition of a methyl group to DNA, is one of the key mechanisms of gene imprinting, leading to gene silencing without changing the DNA sequence.
Step-by-step explanation:
One of the mechanisms by which genes are imprinted is the methylation of genes. Gene methylation refers to the addition of a methyl group to the cytosine base in the DNA, particularly within CpG islands of the gene's promoter region. This methylation often results in the silencing of the gene and can be transmitted from parents to offspring, making it heritable. This process does not involve a change in the DNA sequence itself but rather a reversible chemical modification to the DNA. Epigenetic changes such as methylation play a crucial role in regulating gene expression without altering the underlying genetic code and can be influenced by environmental factors and life-style choices.