Physical characteristics in identical twins change over time because of environmental factors. The epigenome changes because of the environment. The epigenome turns genes on or off depending on signals from the environment.
Some environmental factors are diet, stress, exposure to toxins, and physical activity.
An imprinted gene is an epigenomic tag that stays on during the reprogramming process, which usually erases tags so that stem cells are created.
Some factors that could be affecting my epigenome are video games, taking a high level math course, my mom being in graduate school, and of course my siblings.
A high nurturing mother rat activates a pup's GR gene, which, when bound with cortisol, sends calming signals in stressful situations.
Licking by a mother rat activates a pup's GR gene. The function of the gene is above.
GR and cortisol need each other to function. In stressful situations, cortisol is released, but if the is low GR, not many calming signals will be released. This causes the pup to be more anxious, which can be a benefit in the wild.
Human parents involved with their kids and respecting them seem to give off a caring but not overprotective feel. Overprotective parents annoy their kids and then the kids in turn don't pay much attention to their children because they wanted less involvement, and vice versa.
Food we eat affects our epigenome, because folic acid creates methyl tags, which in turn activates/deactivates genes.
The diets of parents greatly affects the epigenome of the offspring. In one Swedish town, periods of plentifulness during the ages of 9-12 in males affected their grandchildren. Periods of abundance make grandchildren more at risk for heart disease, and vice versa.
Dietary methyl influences the epigenome in the ways of turning genes on and off. More methyl means more genes off. The methyl usually comes from folic acids, which is why the acids are a necessary part of nutrition.
Toxins affect gene methylation in the way of triggering changes throughout the epigenome. This effect is why it is very difficult to break addictions, from drugs to nicotine and alcohol. The changes stick around, so they are responsible for relapses in drug abuse and addiction.
