I don't know if it's on-topic, but "trust your parents" seems to be a pretty good heuristic, evolutionarily speaking. Your parents were successful enough to produce at least one child, and the advice they give will be tuned to your genetics and environment more than average.
An obvious side-effect of this is that you will believe a lot of stupid stuff that your parents tell you.
(Even more off-topic: do people with more siblings trust their parents more?)
and the advice they give will be tuned to your genetics and environment more than average.
Nitpick: Having offspring is not sufficient for being above average in any evolutionary sense. Though the original point (believing parents due to them usually being helpful to you for survival) still stands.
And not off-topic, but actually interesting. But as in other cultures upbringing and education is often more strongly associated with a larger part of family and also the peer group, I doubt we would see much there.
Today I received some shoes in the post, which included a couple of packets of silica gel. I don't think I have ever seen a packet of silica gel that didn't have "DO NOT EAT" printed on it, and it's always bemused me. It doesn't look edible, or smell appetising, and isn't even especially harmful to ingest in most circumstances. Chances are that if I ever did want to eat silica gel, I'd probably have a damn good reason, and a lifetime of being told to not eat it is an obstacle to that.
This has started me thinking about all the other things we internalise as serious hazards contrary to reality. As a child, I was told that picking my nose and eating it would have some sort of cumulative toxic effect. This was obviously a lie manufactured by my parents (or maybe their parents) to get me to stop doing it, but a couple of decades later I felt positively scandalised when I read about an Austrian pathologist who claimed the practise was beneficial to the immune system. (Although this is mentioned in the delightful Wikipedia page on nose-picking, the reference links are dead, so I'd actually treat this assertion with caution, but feel free to munch away on your own dried nasal mucus anyway).
Although nose-picking and eating the packaging that shoes come in are pretty trivial examples, I do wonder how many of these prohibitive false dire consequences I'm still labouring under, invisibly making my life more difficult. I also wonder how many full-grown adults still don't accept sweets from strangers.
Do you have any examples of an authority figure, or a prevailing piece of cultural conditioning, giving warnings of dire outcomes you later discovered to be false, misleading or based on an agenda you were naive to at the time?