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Team_Ed t1_ivyfast wrote

Reply to comment by CharlesOSmith in Does malnourished parents effect how tall your final adult height would be? by [deleted]

Is there not a genetic effect re selection and survivor bias?

It wouldn’t necessary apply to any given individual, but a population that experiences one or many large malnourishment event(s) — periodic famines or, say, the holocaust — will end up seeing smaller body types survive at higher rates simply because bigger bodies are harder to feed.

So if you are the descendant of a famine survivor whose body was wrecked by the experience, their personal experience may not directly effect their kids’ genetics regarding body size, but it may nevertheless be true that those kids might be more likely to have their genetics tend that way, regardless.

Obviously wouldn’t apply if we’re talking one-off malnourishment events like individual poverty, but then many people in the west who might have parents with these personal histories or malnutrition are from immigrant populations that may have those selection pressures.

ie: if your parents were malnourished, it’s logically more likely they come from a population where malnourishment is common and small size is genetically selected for — meaning you may be more likely to have small-size genes regardless of whether your parents had been malnourished.

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Aceticon t1_ivyi214 wrote

Genetics works at a much more massive scale (numbers and time wise) unless there's the kind of trully exceptional circumstances where almost all individuals of a tribe perish without leaving any descendands (in which case only the genetical material of the survivours could possibly carry on forward), so most of it is to do with tiny differences in the probability to reproduce which over many generations and across millions of individuals cause a certain characteristic to become preponderant.

So a single generation (or two or three) going through starvation wouldn't do much to the genes themselves unless it was so extreme that the "only handlfull of survivors, no living descendents for the others" situation happenned (and even then it would only affect that tribe and might later dilute itself to non-existence through intermixing with other tribes)

Epigenetics on the other hand has to do with proteins that surround the genome but are not the DNA itself, which can toggle genes ON/OFF or influence their expression, which can change during an individual's life due to environmental factors and which can also be passed from parents to children. It seems to be a far more reactive mechanism but also one which is more temporary.

Whilst epigenetics also has to do with genes, it is something only recently discovered and in it the information is not stored in the DNA.

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