Darwinsbulldog wrote:@Federico

I thought epigenetic licencing was an accepted term?

I'd consider it a colloquial expression rather than a scientific one but I am no expert in semantics and, in any case, I find much more fascinating the spate of new discoveris about the role of epigenetics in human evolution such as this one I reported last year in this Forum and which is entitled: "Can Smoke-Induced Cancer be Inherited?"

"To quote the distinguished Oxford- based neurologist, Professor George Ebers:
"The articles that have begun to appear in medical journals suggest that the environment is constantly altering gene expression through the modification of [its] profile”. They say that “an ‘epigenetic' mark may be added to or removed from gametic DNA [containing sexual reproductive cells] in mothers”. They add that “these changes may remain through cell divisions for the remainder of a cell's life, and sometimes these changes can last for multiple generations”.

This hypothesis becomes even more cogent after reading the article published recently in Medical News, titled "Cancer-Linked Epigenetic Effects Of Smoking Revealed By Study" and presented at the 35th Congress of the European Society for Medical Oncology (ESMO) in Milan, Italy.
[i]The link between smoking and cancer has been established for decades, explained Dr Yuk Ting Ma from the Cancer Research UK Institute of Cancer Studies, Birmingham, who presented the results. Smoking is the single biggest cause of cancer in the world, and years of research have confirmed that carcinogenic substances in tobacco smoke can damage DNA.
Scientists have also suspected that smoking causes so-called epigenetic changes, such as methylation, which alter gene expression without causing changes to the actual DNA sequence.
The particular gene the researchers were studying was p16, a so-called tumor suppressor gene. When it is methylated, this gene's normal tumor-suppressing function is inactivated.
"DNA methylation is a type of epigenetic change that can result in tumor suppressor genes being inactivated," said Dr Ma. "Methylation of p16 has been frequently associated with the development of cancer in many parts of the body."
Our study showed that compared with never-smokers, women who first started to smoke during follow-up had an increased risk of acquiring methylation of p16," Dr Ma said. "Our choice of study design and our study population allowed us to reveal, for the first time, the relationship between starting to smoke and the subsequent appearance of an epigenetic change".

And I added this comment:

"Although not mentioned in the article, it is quite possible that smoke-induced, cancer-producing epigenetic changes of suppressor genes expression may also be transmitted to the offspring."