Princeton loves its legacies. There was an article in the Daily Princetonian that legacies were admitted at about a 42% rate vs. a 7% rate for others( see below). I think a FIL is close enough for them.
http://www.dailyprincetonian.com/2010/05/12/26151/ -
For the Class of 2013, the University admitted 42 percent of legacy applicants, who made up 2.5 percent of the total applicant pool, compared with nine percent of non-legacies — a difference in admission rates of 33 percent. This is only a slight drop-off from the roughly 35 percent difference in admission rates in 1958.