Oddly phrased-- sorry!!
My aunt and uncle have worked at Vanderbilt for years, and I am very close with the family. She’s not my direct aunt (my mom’s cousin), so I know it’s not an automatic admission, but she is the department head of psychology at Vandy and she offered to write a letter of rec to the CT admissions officer (where I’m from)… how much of an impact does this make? I know it’s not legacy and it’s not like she is my mother/directly related, but does it help? I read the letter-- it’s more personal than academic. She talks about me as a person (childhood memories) and some academic achievements that she herself witnessed, such as my national history day documentary which went to nationals, but she didn’t talk so much about my environmental background since she is a psych teacher… thanks in advance! 
Can’t hurt but probably won’t help either.