The rule could be anything, as funny or as serious as you want. The universe will progress in a similar way that it has up until this point, unless your changed rule prevented it from doing so.
Some examples might be:
- The invention of currency is not allowed.
- Iron is slightly less stable.
- The Ancient Greeks are able to cultivate Silphium, which does not go extinct now.
It’s little ones like this that have such insidious implications.
Even without a evil genie rule… No stds.
Which means that sex has no touching
Or
Everything is super fucked up - bacteria/viruses/fungi can no longer transfer from creature to creature through touch… I don’t have the knowledgebase to even imagine what the results of this would be but I think somewhat catastrophic…
±------+
Also wood would be dense as fuck. Damn.