My father attended Princeton as an undergraduate and has donated at the school. How important is legacy?
I am sure it helps for borderline cases, but the importance of the legacy bump has diminished over time as the highly selective universities have been on a mission to diversify their student body. In the late 70’s to mid '80’ss, legacies made up over 20% of the class at Yale https://oir.yale.edu/sites/default/files/pierson_update_1976-2000.pdf. Today legacies hover between 10-15%. I am sure Princeton shows a similar trend. Maybe some Princeton alum’s and parents have similar figures at their finger tips.
Admission rates for legacies are still significantly higher for legacies than the overall rate by multiples. However, the fact is that legacy applicants are going to represent a much stronger pool than the average. Most will have all the higher SES advantages of a strong educational foundation and resources for prep, EC’s etc… , and they are probably also more familiar with the school in terms of expressing “why X.” My understanding from the Yale AO is that legacies have on average slightly higher test scores than other matriculates.
So, if your app is not already strong, legacy will not help get you over the bump. In fact you will likely be unfavorably compared against generally high achieving legacies that are also applying. If your app is strong, it might be the tip that gets you in.
As to donations, unless your dad has given/will give 7+ figures, it won’t make much of a difference. If he has given generously and consistently, it might be an added plus. I don’t know Princeton’s policies on communications between development and admissions, but for Yale, development is allowed to add a “note” to the applicant’s file. However, there is a quote from a Yale dean of admissions floating out there on how many rejections there were of children the highest class of Yale donors. Anecdotally, among classmates that I keep in touch with, there was no correlation between acceptances and donations.
Being a legacy will help your application and could give you the edge over other similar non-legacy candidate – but legacy status won’t get you into Princeton if you are not otherwise qualified to attend (unless your father donated a building).