<p>There are two different kinds of legacies when it comes to college admissions. One is a legacy in the sense that a parent or sibling went to the school, had no financial involvement with the school, and the college might be more apt to take that applicant when considering them against another applicant with the same stats that they are also considering taking in the hopes of continuing a school connection ect.
The other kind of legacy is the kind where one has a parent or grandparent (even if they say grandparents are not legacies) who is very important to the development office of that school. That is a parent or grandparent who has graduated from the school (the undergraduate school) and has been involved often over decades, and has made substantial financial commitments to the school over time. This person if often seen as someone who will continue to make contributions and continue that connection. In that case, where that child or grandchild applies to that school, where their grades and scores are in the range that the school usually accepts, that applicant is usually given a substantial advantage in terms of being accepted.
Where someone has an uncle who attended the school, and is an important figure, it might help to have the uncle write a personal letter on behalf of his niece or nephew. It may be an advantage but might not be significant</p>