Inspired by an argument with my sister last summer.
We were talking about genetics, and she put forth the idea that a parent’s experiences could be reflected in their offspring’s genetic code. A parent who habitually didn’t get enough food, for example, might have offspring genetically geared toward less production of fat (or something like that, I forget what the exact example was).
To me this sounded Lamarckian and Lysenkoesque. Which genes you express, I said, can certainly be affected by environment; but I was under the impression that your DNA was something of a black box. A parent’s environment did not affect which genes were passed along to the child (absent, of course, something like a radioactive environment).
But she said she’d heard a news story about something like that on NPR. So I’ve been meaning to ask y’all, and now I have.
I’m sure she heard something about epigenetics, yes. The short answer is that yes, but not always in the ways that you’d expect, and sometimes the changes aren’t seen until the third generation (that is, your grandchildren). It’s pretty wild, though. A teacher once (probably vastly oversimplifying) referred to it as the effect of “turning” genes “on or off” without changing them. So you get things like grandsons of men who suffered famine as children were themselves less likely to die of cardiovascular disease. None of the DNA changed to cause this, but some genes were activated in the grandfather’s famine experience that were then passed down somehow and expressed in their son’s sons - but not their sons, and not their son’s daughters. And, just to get even more confusing - the opposite is true for women. Women whose grandmothers suffered famine as children are more likely to die young. Weird, right? I don’t begin to understand it, but it is believed to be a real thing.
Yes, epigenetics is making a huge splash in the public mind at the moment. Personally, I think its importance is being a bit overexaggerated, but whatever. The idea is that DNA can be modified with various markers, like methyl or acetyl groups. The DNA sequence itself is not changed in any way, but these markers can affect gene expression, and can be passed on from one generation to another.
I found this from a course on epigenetics I once took (sorry, don’t have a cite for the data):
Dutch Famine Birth Cohort Study
• Increased disease propensity associated subtle changes in DNA methylation of a small number of genes e.g. IGF2, GNAS and MEG ICRs (imprinted genes) and other metabolic genes
i.e. some evidence of epigenetic alterations, and at some “sensitive regions”, similar to IVF/ART data
• Original data suggested transgenerational effect of Dutch famine, but follow up, better controlled, data suggests there is no transgenerational aspect