Epigenetics. It's the make-file for your genetic source code. Certain conditions can cause certain parts of your genetic code to be uncommented or commented-ou

Epigenetics. It's the make-file for your genetic source code. Certain conditions can cause certain parts of your genetic code to be uncommented or commented-out. There are actually a number of different kinds of comments (histone modifications [1]) - each set of marks particular to a different compiler, in different contexts. And these comments/marks are copied with some fidelity to daughter-cells/children. So the genes themselves are not being heritably altered, rather the recipe for which gene is where, when can be subtly changed. But again, the same mechanisms that permit the change in expression of those genes during a lifetime can be subsequently changed in the next just as easily. [1] https://en.wikipedia.org/wiki/Histone_code https://en.wikipedia.org/wiki/Histone_code