The answer is true.
DNA methylation is a process by which methyl groups are added to the DNA, more precisely to its nucleotides adenine or cytosine (they are methylated) via enzymes called DNA methyltransferases. This process as a result can change the activity of a DNA. For example, if DNA of gene promoter is methylated gene transcription is repressed. The opposite process is DNA demethylation.
So, DNA methylation is an epigenetic mechanism meaning that gene activity can be changed and inherited that way, but the sequence of DNA remains the same.