If your mother experienced a famine while you were a third trimester fetus, this messes up your metabolic programming and increases your risk for metabolic diseases – in ways that can cascade down to your own children epigenetically.
During their occupation of Holland in 1944, the German administration placed an embargo on food transports to punish the locals for a railway strike. This created a famine from November 1944 to May 1945, during which affected natives ate as little as 400~800 kcal/day. Access to food returned in May when the Allies came in, so you had a sudden jump from plenty to scarcity, followed by sudden jump from scarcity to plenty. (This famine is called the Dutch Hongerwinter, and this writeup is largely from the 6th lecture of Robert Sapolsky’s human biology series – the 5 minutes starting here.)
If you were a third trimester fetus during that winter, you likely had a different metabolic phenotype than the rest of the population: your body was better at retaining salt, storing away nutrients in the bloodstream, being thrifty with energy. There was a nineteen-fold increase in hypertension, obesity, diabetes among this microgeneration – their bodies had kind of learned during a formative period that the world out there is a world of famine, let’s grow into something that deals well with scarcity.
And when members of this microgeneration reproduced, they pulled more-than-average amounts of nutrients out of their bloodstream during pregnancy, leaving less for the fetus, who in turn ‘learns’ that the world is a world of famine. This is a mechanism for inheriting a non-genetic trait.
Something similar has been found stressed rats – if a female rat is stressed during pregnancy, the stress hormones affect the brain development of its children, who throughout their lifetimes will be less good at regulating stress. And when those rats get pregnant, their own children will be affected by the higher level of stress hormones in the bloodstream. Apparently it took about 4 generations for this stress echo to die out.
Unrelated to the metabolic consequences: being conceived at the height of famine increased your risk of being schizophrenic, ‘a finding subsequently replicated in a study based on the Chinese famine of 1959-61′.