Epigenetics refers to the inheritance of characteristics, when cells divide and multiply, that cannot be attributed to changes to the DNA sequences. Each person has a unique set of these characteristics, termed an epigenome. So in addition to the genetic material encoded by the DNA (the genotype) each of us has a set of epigenetic characteristics that determine the differences between individuals (their phenotype).

Epigenetic characteristics of each individual are based on chemical changes on a chromatin that allow either more or less access to genes within a specific region of the chromatin. With more access, genes can become active and the information encoded by the genes can be used by the cells. With less access, genes become inactive: the information encoded by the affected genes cannot be used by the cells. Acetylation of the chromatin is responsible for creating more access to the genes. On the other hand, methylation of the DNA closes access to the genes. These chemical changes to the chromatin and the DNA can be permanent or reversible.

Recent experiments indicate that epigenetic changes could be passed on from parents to their offsprings. There are well over 100 scientifically documented instances for epigenetic inheritance. Here are three examples:

1. Bees in a hive are genetically identical. But depending on the diet they eat, bees develop either into a queen bee or a worker. It was shown that diet led to epigenetic changes that led to silencing or activation of a specific gene responsible for determining the future life of a bee.

2. Eye colour in fruit flies can be changed by raising temperature. When embryos were exposed to 37°C they developed red eyes. Their offspring, when cultured normally, had partly red eyes as well and no changes in the gene, responsible for eye colour, were observed.

3. Nurturing experiences are passed on from parents to their offspring. Thus for example, rats that exhibit high levels of nurturing have children that also provide high quality care to their offspring.

Yes, the environment can influence the epigenetic profile of an individual. The process is complex, but the end result is that certain chemicals in our bodies can affect the acetylation or methylation processes. Thus depending on the circumstances, the environment may be able to change the epigenetic profile of an individual and influence which genes become active and which not.

Epigenetic profiles (epigenomes) of individuals are influenced by the environment. This means that, through the epigenome, the environment can influence which genes are activated and which genes remain silent. Some of the environment induced stresses may negatively influence the epigenetic profiles. As epigenetic profiles could be passed on from parents to their offsprings, it is important for parents to think about their lifestyles. For example what they eat, where they live and how they live. The good news is that unlike changes in the genes themselves (for example through mutations) where we as individuals have little or no influence over such events, we can influence our lifestyles and thus our epigenetic profiles.

Epigenetic research can help patients in many ways. The underlying strategy is to learn how to manipulate the closing and opening of specific chromatin regions to either allow some genes to become active or to shut down activity of other genes. The research objective is thus to manipulate epigenetic profiles.

Here are two examples where the knowledge of manipulating the epigenetic profiles could be used to improve the quality of our lives:

1. Cancer research - Why does one identical twins develop a cancer while the other does not? After all, identical twins originate from the same fertilized egg and their genetic material is identical. The point is that, as the twins age, they become more and more different from each other due to accumulated changes in their epigenetic profiles. These differences have been shown to be influenced by the different lifestyles of identical twins. As these differences influence their individual epigenetic profiles they also influence turning off and on of their genes. This in turn may lead to some cells dividing in an uncontrolled way explaining why one twin may become ill with cancer, while the other remains healthy. This knowledge, that epigenetic changes may lead to cancer, has already been applied to treat certain types of cancers in patients. Initial results from clinical trials are encouraging.

2. Stem cell research - Embryogenic stem cells have the potential to develop into almost any cell type. But what tells one stem cell to become an eye cell or a muscle cell? The epigenome profile of an individual has an important role in such decisions. It can tell genes when and where to become active and for how long. This helps stem cells to differentiate into a specific cell type. Scientists are learning how to manipulate this process, to tell for example an adult (differentiated) stem cell to change back to become a embryogenic stem cell or to exactly tell a stem cell what cell type it should become. This ability to manipulate the destiny of individual cells could lead to the creation of organs or useful cell types to replace damaged organs or cells in ailing individuals.