> Harvard, and many other colleges, has a big base of "legacy" admissions, as well as a certain amount of generational knowledge and connections - you're more likely to get into Harvard if your parents went to Harvard, over and above mere class status.

Let's explicitly look at how this affected race, since that was the issue the court was asked to consider. The student body of the US Ivy League looked as follows, circa 2019 (international students excluded):

                          Ivy League   US      Ratio  Mean SAT score [1]
  Jewish                  17.2%         2.4%    7.16
  Asian                   19.6%         5.3%    3.71  1216
  White (incl. Jewish)    50.3%        61.5%    0.82  1148
  Hispanic                11.4%        17.6%    0.65  1043
  Black                    7.8%        12.7%    0.61   966
  White (non-Jewish)      33.1%        59.1%    0.56 ~1141 (lower bound estimate)

SAT score seems to offer no benefit, up until the magic cutoff somewhere between 1142 and 1216.

The numbers don't sum to 100% because multi-ethnic students, a few minor ethnicities (American-Indian, Pacific Islander..), and students categorized as "unknown" or "other" by the universities were excluded from analysis. Data on university undergraduate demographics was taken from the universities own diversity reports. Jewish representation was gathered from http://hillel.org/college-guide/list/, https://forward.com/jewish-college-guide/, and https://ejewishphilanthropy.com/how-many-jewish-undergraduat..., taking the lowest estimate when sources conflicted. ejewishphilanthropy.com (eJP) points out flaws in Hillel's data gathering (e.g. showing Harvard as 30% Jewish, when eJP found it only 16%) Hillel seems to have since fixed these flaws, as the estimates they now give are in-line with those of eJP.

No correction has been made to look at only the college-age population of the US, or only at the Northeastern US where all the Ivy League universities are located, so that may be a source of some bias.

[1] https://www.ednc.org/eraceing-inequities-the-influence-of-ra...