In the field of intelligent design, epigenetics is of interest because it usually involves the non-coding portions of DNA, which calls into question the earlier paradigm in genetics that only the coding portions of DNA are of significance for phenotype, and because it signifies an additional layer of complexity to the genome, calling into question the neo-Darwinian assumption that life is built from the bottom-up rather than the top-down.

Take leukemia, for example. While great strides have been made in detecting and curing some types of cancers, the question of what causes cancer remains fuzzy. Indeed, lifestyle choices can obviously play a role. Smoking has been linked to lung cancer, and sunbathing to melanoma, but not everyone who smokes gets cancer, and not everyone who is out in the sun gets melanoma. Some people get these cancers without the behavior.

This disparity may be due to a combination of environment and genetics. The incidence of breast cancer, for instance, may be linked to the BRCA genes, but not everyone who has these genes gets breast cancer, while some people get breast cancer who do not have the genes.

Leukemia, for its part, seems to have a genetic component and an environmental component, but scientists are not sure what they are. Now several cancer research centers are looking at epigenetic factors as a possible indicator. In particular, they are looking at methyl groups, which are small chemical components that attach to DNA. These little chemical flags may affect DNA in many ways, including how the DNA folds around a histone. Scientists have found that there seems to be a link between mutations in the enzymes that insert or take away the methyl group and the incidence of leukemia. When these enzymes are not working the right way, the chemical flags are incorrect, causing the DNA to fold improperly.

The prevailing paradigm had been that if a disease has a genetic link, it would be due to either a mutation in the sequence of A’s, T’s, C’s, and G’s, or the insertion of a piece of DNA sequence. Current research on epigenetics suggests a different perspective. As Timothy Ley comments in the Nature article: “A couple of years ago, if I had said that to somebody they would have laughed me out of the room… There just was no clear notion that epigenetic modification would be so critically important for the pathogenesis of the disease.”