The human genome and epigenetics

So as many of you may or may not know, they've mapped our entire human genome. What that means is that they have long lists of letters that are put together in certain ways that map out exactly what protein-coding genes, RNA, etc. go where, and do what in the human body. Our genome is within percentage points of being the exact the same as rats, monkeys, and a few other mammals. For a long time people have thought that our health, our psychological tendencies, our addictions, and our physical appearance to be the sole product of our genes. Recently research has been illuminating the other side of that argument. I recently watched a NOVA special called Ghost in Your Genes.

Take for example, identical twin girls, according to our understanding of the human genome they have the exact same set of genes and DNA. Those twins reach the age of 60, and one twin develops cancer while the other one does not. Take another set of teen adolescent identical twin boys. At the age of 3 one boy starts to drift into his own world and has a harder time interacting with human beings, or anything live. He starts to obsessively spit on the computer monitor and wipe it clean, over and over and over again. He was eventually diagnosed with severe autism. The other twin boy excels at school, is an athlete, and talks of the colleges to which he will apply.

If genes are the only things at play here, how do identical twins, with exactly the same genes and DNA, divert so greatly in the physiological or psychological symptoms they present?

This is where epigenetics comes into the story. Taken directly from Wikipedia:

Molecular basis of epigenetics

The molecular basis of epigenetics is complex. It involves modifications of the activation of certain genes, but not the basic structure of DNA. Additionally, the chromatin proteins associated with DNA may be activated or silenced. What this means is that every cell in your body has the same instruction manual, but different cell types are using different chapters. Your neurons, for example, contain the DNA instructions on how to make your fingernails- but in neurons, those genes are turned off. Epigenetic changes are preserved when cells divide. Most epigenetic changes only occur within the course of one individual organism's lifetime, but some epigenetic changes are inherited from one generation to the next.[9] Specific epigenetic processes include paramutation, bookmarking, imprinting, gene silencing, X chromosome inactivation, position effect, reprogramming, transvection, maternal effects, the progress of carcinogenesis, many effects of teratogens, regulation of histone modifications and heterochromatin, and technical limitations affecting parthenogenesis and cloning.

Epigenetic research uses a wide range of molecular biologic techniques to further our understanding of epigenetic phenomena, including chromatin immunoprecipitation (together with its large-scale variants ChIP-on-chip and ChIP-seq), fluorescent in situ hybridization, methylation-sensitive restriction enzymes, DNA adenine methyltransferase identification (DamID) and bisulfite sequencing. Furthermore, the use of bioinformatic methods is playing an increasing role (computational epigenetics).

These epigentic chemicals can tell which parts of a strand of DNA to be expressed, and which to be turned off. These epigenetic switches can be mediated, and modified by diet, environment, stress levels, and even the stress levels and amount of food your grandparents had to eat. I recommend the "Tale of Two Mice" interactive on the URL I listed above.

Nuture is getting more press, it's getting more research, and for this little bodyworker, the line between mind and matter is thinning at an outstanding rate.

Thoughts?