If a single person does something without fully realizing he did it, or why, it could be said to be done subconsciously.
A group of people can likewise develop a cultural tendency, or meme, without the individuals who propagate the meme being conscious that they are propagating it, or why they do it. For instance in an area where starvation is more common the idea of 'beauty' may include a heavier set women, a subconscious preference for someone who is clearly not starved and thus likely healthy and financially well off. While the majority may agree with this vision of beauty they may not be consciously aware of why it is important to them. The meme has spread through the culture without a conscious recognition of its spreading or what motivated its existence.
Is there a good term to express these sort of memes? Specifically I'm looking for a word/words to allow me to discuss the cause/motivation of a meme while acknowledging that the culture the meme originated within may not be consciously aware of this cause.