Epigenetics?

Did you mean ' I dont understand how such a change can be heritable if the DNA is NOT changed?'

Because it alters the sequence of amino acids as opposed to the DNA sequence itself

Basically epigenetic tags can bind to the DNA and prevent expression or start expression of a gene, and this is within the genome, not the actual DNA sequence. The epigenetic marker can sometimes not be removed during meiosis, which is why the expression of that gene can be heritable- as the child has the same epigenetic tag on its genome as the mother.

Whilst the genome remains intact, epigenetic tags including methyl groups and histone modifications are made. Its a way for evolution to work, to adapt to our environment, without changing the sequence of DNA.
At any one moment within our genome there are millions of inactivated genes that can be activated by these groups.

In history, we often see that after bouts of famine. offspring from the affected are more likely to eat more and become obese because they have a behavioural and physiological tendency to adapt against the famines.
The bee and the queen bee are actually genetically identical, yet differences in their morphology rely entirely upon epigenetics.

Behavioural epigenetics is why we associate fear with insects for example even today. (we are currently doing research in this field)

If I were too shock a rat and associate the shocking with a smell, the babies of these rats would grow up scared of the smells.

Another example is in the past. Asian and African mammals had behaviourally accustomed a fear towards early forager homo sapiens whilst retaining their genotype, due to excess hunting.
However, when the first foragers moved to Australia, many large mammals such as the diprotodon (now extinct) had not experienced epigenetic changes to their behaviour, and had not associated fear to humans. This resulted in them not fearing humans, and hence they were much easier to hunt.


A more common example is seen in us humans!
Harvard researched followed 730,000 people for all cancer types and deduced that those who were married were 20% less likely to die even when controlling for factors like medication consistency and appointments.
Epigenetics has shown us the importance of social relationships on gene regulation.
The same difference is seen in cortisol receptors in human suicide victims that were abused in their childhood.

I think I should shut up now.

We do not inherit from our parents a single biological identity. Our genomes encode a vast range of potential selfs depending on our environment.