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The reset happens in the days following fertilization. Pretty much 100% of human DNA gets demethylated then.


1) epigenetic inheritance is just if a horse stretches its neck to reach up high, so to do that horses children and their children, and so on, until you end up with a giraffe

2) yes methylation and epigenetics resets, not so much at meiosis as at conception zygote formation

3) it doesn't 100% reset more like 98.3% resets, the remainder does NOT reset, thus, epigenetic inheritance. Sometimes that reset process fails, thusly, (epi)genetic disease. Also all this process called "imprinting" is why it was hard to clone various organisms including until recently humans - you can "reset" a skin cell 100% but that's not the ticket, you need to reset it 98.3% and leave the imprinting regions. Oh. And the specific imprinting regions are different for the chromosome that come from mom, vs, the chromosome come from dad

So the big takeaway is that DNA no longer is the main mechanism of inheritance as Darwin taught but actually epigenetic, and the basis is along the lines of horses stretching their necks and becoming giraffes. There's a lot of getting into the weeds as to how this all works molecularly is that's it's really complicated but it is inherited




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