Then you get examples like Marcus Aurelius -> Commodus, betraying all genetic and epigenetic reason alike. The apple doesn't fall far from the tree, except when it does.

Study finds epigenetic changes in children of Holocaust survivors https://www.research.va.gov/currents/1016-3.cfm

I often wonder if my Irish ancestors genes passed on trauma through my family to me. With 900 years of invasion, war, famine, and strife you'd think something like that would be passed on.

Huh? The article is able to summarize in one sentence what he thinks epigenetics is not, but is not able to summarize what it actually is. The post is clearly designed to make the reader feel like they are smarter than some other tribe, who don't believe that observations have molecular underpinnings. The Post-it notes analogy is also highly inaccurate and adds nothing.

Epigenetics is one way that cells have of turning on and off the genes that are expressed. The same way that you can 'comment' a piece of code out using some special flags.

What is special about it is that it turns out that your mom's experience during pregnancy (and your experience during development) can affect which genes are turned on and off in your cells.

The classic example of this is that children of starving mothers such as during the holocaust, or during other famines, often went on to be overweight, because they were conditioned to be in 'starvation mode' so the genes for uptake of nutrients were more turned on, or the genes for decreasing wastefulness were turned off.

It doesn't take much imagination to see how some of these things could reinforce each other, or alternate, over multiple generations.