What do American university admissions processes have in common with those of Chinese universities prior to the Cultural Revolution?

Hmmm. Ideologically based affirmative action which prioritize admissions on factors other than capability.

From Gail Heriot in REMEMBERING THE CHINESE CULTURAL REVOLUTION’S RED AUGUST (ADDENDUM). I had not realized that Mao was secretly a biological determinist and fan of Gregory Clark's work.

Red Guard students also tended to be the beneficiaries of preferential treatment in admissions. All during the 1950s and 1960s, the children of party members and at least in theory the children of peasants and workers received a kind of “affirmative action” in admission both to elite schools and to colleges and universities. Frequently a revolutionary pedigree was a more important credential than a good academic record. Early on, a popular meme (if not exactly a Shakespearean couplet) was “If the father is a hero [of the Revolution], the son is a good fellow; if the father is a reactionary, the son is a good-for-nothing—it is basically like this.”

Like students who receive preferential treatment here in the USA—diversity students, legacy students, and athletes—on average the Chinese recipients of preferential treatment got poorer grades than other students. Mao is reported to have acknowledged this: “The political performance of the children of revolutionary cadres in schools can only be rated as second-class, but students with bad family backgrounds [i.e. the children of alleged capitalists, landlords, rich peasants, and counter-revolutionaries] have performed very well. However, no matter how well they have performed, revolutionary tasks cannot be put on their shoulders.”

"The political performance of the children of revolutionary cadres in schools can only be rated as second-class." There is some tart comment in there about Journalists and the Mandarin Class.