Well I hate to disagree with post #4. Kid #2 didn’t show any interest at USC because her big sister went there and she’s been at USC many times. She didn’t do any tour, didn’t talk to the adcom when he visited her high school, no interview , nothing. She was accepted to Viterbi for Computer engineering.
She had strong letters of recommendations from an MIT program, strong SAT scores and strong GPA. I don’t think her essay was strong but it was not terrible either, perhaps having a sister who went there and did well at USC was a big plus. But it’s not a legacy or anything.