Which process can lead to the silencing of genes through the addition of methyl groups?

The process that leads to the silencing of genes through the addition of methyl groups is DNA methylation. This biochemical process involves the addition of a methyl group (CH3) to the cytosine base of DNA, typically occurring in regions of the genome known as CpG islands. When methylation occurs in gene promoter regions, it can inhibit the binding of transcription factors and other proteins necessary for gene expression, effectively silencing the gene.

DNA methylation plays a crucial role in various biological processes, including embryonic development, genomic imprinting, and the maintenance of cellular identity. This silencing mechanism is vital for regulating gene expression and maintaining normal cellular function. Conversely, the other options do not involve the addition of methyl groups. DNA recombination refers to the rearrangement of genetic material, DNA demethylation involves the removal of methyl groups, and RNA splicing is related to the processing of RNA transcripts and does not directly impact the addition of methyl groups to DNA.