I don't think it was entirely intentionally done from the foundation, but more just bad investigative work done by single minded police. Like I said in another comment, they used Ed Kemper to basically build their blueprint, which is what created the "high IQ, soft spoken/polite, sexually frustrated and hates their mom" standard that they brought into every other case.

And then the media latches on to it, spreads it everywhere, and then because women love murder porn they repeat it constantly. Which then creates this idea in everyone's head that its this constantly repeated pattern, despite being pretty much only a handful of examples.

For example, its not just a race problem. Serial killers have a huge overrepresentation of faggots too, but because of that same Kemper blueprint nobody focuses on that even when very gay serial killers are literally being talked about, like Gacey or Dahmer.

So like always, its the media creating nonsense from half truths and then people swallowing it without a thought until it literally influences their perception of reality.