Perhaps:
When people come from families that have been educated for generations, it's expected that they become educated. They exercise their brains from a young age. Especially since the family has had evidence that education is well rewarded.
When people come from families that have never been educated, that have a history of oppression, and have no evidence that education is rewarded, those people tend to by cynical towards education and intellectual development. They do not exercise their brains.
That results in lower IQs.
Ah the good ol' systemic oppression canard.
If systemic institutional oppression were a real thing, Whites would have the highest levels of income attainment.
However, they don't Asian Americans do. How did they manage to avoid systemic oppression? Did the system just not apply the great injustices of the world to Asians?
White Americans - Wikipedia