The primary culprit is shit-tier memes. Indoctrination with the memes of stability and prosperity would go a long way (see the brief period between 1920 and 1960 where they had both rights and responsibilities), but once the external pressure to be moral actors is lost (or intentionally subverted) you get this pre-tribal behavior all over again.

Even Europeans have begun to degenerate under the pressure, and their genetic stock were the first adopters and propagators of decent memes.

I don't think we have definitive proof that there's a genetic inability to adhere to good memes, even if there's a noticeable lack of organic development of them.