"Ahhhh! But we don't know that. Memetics is not genetics."
No, but it's a perfectly good starting point for a hypothesis. Memetics may not be genetics, just like how ducks might not be crows. But, like how ducks and crows are both birds, memetics and genetics are both means of conveying/replicating/mutating information.
"But what if I told you my smaller population sample was from a university and the larger one was from a prison."
What if you told me such a thing? Would you be implying that prisoners come up with fewer ideas than universities? From what do you derive such an implication?
"I suspect myself that intellectual diversity is orthogonal to the physical phenotype of diversity."
On paper, it is.
In practice, intellectual characteristics correlate strongly to educational background, which correlates strongly to socioeconomic class, which (at least here in the United States) correlates strongly to - you guessed it - physical phenotype. Some people break out of those correlations, but they're (last I checked) the exception, not the norm.
This is by no means anything inherent in those phenotypes, of course. You already know that. Rather, it's a systemic issue: one of social norms and preconceived notions. We can pretend that everyone's equal, but it ignores the core of the issue: that the segregation of viewpoints still exists, and thus still requires conscious effort to correct that segregation.
Intellectual diversity, in short, correlates with phenotypical diversity, since viewpoints correlate with phenotypes thanks in no small part to our world's rich xenophobic history.
"In my previous post in a different thread I wrote something related to this subject which is that Facebook (users) has a lot of genetic diversity in its population but it's a sterile wasteland."
I'd argue that has far less to do with the users than it does Facebook itself.
"Facebook and Twitter are tourists on the Internet, but 4chan, reddit and HN are like natives."
I don't blame you for believing that; it's natural to believe that we're somehow "special" because we happen to be chatting on some forum run by some venture capital firm. Never mind that even HN's users, let alone reddit's (and possibly 4chan's, but I don't really venture over there all too often), have no problem with posting links to Twitter posts for "karma", or that Medium (a favorite among HNers, so it seems) required logins using either Facebook or Twitter until only very recently.
The flow of thoughts between the "tourists" and the "natives" is very bidirectional in reality, and Facebook and Twitter (and Instagram and $DEITY-knows-what-else) might as well be natives at this point, too.