It IS mostly cultural. There are many very smart black people in this country, we just never see them because they aren't considered 'cool'. Even worse, if they're not sucking up to the Democrats, they are considered 'Uncle Toms' and are ignored by the media, when they're not being vilified by it.
Until black parents demand that their kids stay in school and stop trying to act ghetto like the latest gang banging rap star, they'll continue to be poor and uneducated, and it will be no one's fault but their own.
Rhetoric error...no such construct, only baby mamas and sperm donors are producing the spawn that "achieve" such dismal results as noted in the OP. You had it right in your first paragraph and we've been on this slippery slope for about 40 years so it's a long slog back up the hill.
The dummies are not allowed to immigrate.