Epigenetics and The Environment

One set of genes from one parent and one set of genes from the other are combined to make an embryo
The epigenetic tags from the parents are erased, but sometimes they are not all erased. These are called imprinted genes. They are genes that are passed down from parent to child.
Identical twins have the same genome and epigenome
As twins age, their environments differ and their epigenomes change. Their genome stays the same though.
Diet and exercise for instance has an affect on the epigenome as well as exposure to toxins and stress.
Twins share the same environment up until a certain age and it is after then that they start to show signs of changes in appearance.
With genetic diseases, 50%of the time, identical twins both get the same disease whereas with fraternal twins, that is only a 10-15% chance that they will both get the disease.

Lick your rats-
The pups response to the nurturing mother will be that they will be calm adult a and the pups that are not nurtured will be anxious and stressed

Licking the rats activates the pup's GR protein.

Cortisol releases stored energy which is good for fight or flight and the GR protein releases adrenaline which triggers stress. When cortisol binds to the GRs, the hippocampus sends signals to shut off the stress circuit. Rats with higher levels of GR can detect cortisol and recover from stress faster which makes them more calm than rats with less GR.

Humans are influenced by the outside world as far as epigenetics goes and their levels of proteins can be changed. This means that even though they may gave a low nurturing mother, they may end up being very calm because of other experiences they have.



Folic acid, B vitamins and SAM make a methyl pathway . Methyl donating nutrients can alter gene expression during early development.

The mother's diet can affect the offspring because when the diet is unmethylated, people will be more susceptible to obesity and cancer and these traits will stick with the child for the rest of their life.


Methyl levels are high on the RNA in the hippocampus and the more methyl a person has, the less RNA production which leads to less proteins. This will affect gene expression because with the histone modifications, the methyl can help stabilize gene expression.

Drugs that are made to diminish a disease may work that way, but while destroying the disease, they also change the gene expression and the DNA methylation stabilizes the gene expression.