Researchers from the Columbia University Medical Center in New York have now examined whether a specific epigenetic modification (more specifically, methylation of the DNA) can be associated to breast cancer family history in unaffected women from high-risk breast cancer families. This important work suggests that the levels of DNA methylation in white blood cells from cancer-free women could be one of the factors playing a role in the clustering of breast cancer in families with extensive cancer histories within its members.
source : http://www.sciencedaily.com/releases/2014/01/140107172017.htm