I have a famous cousin that went to Amherst (like if you look up Amherst he is under notable alumni). I understand that usually colleges don’t count cousins as legacy, but would this be different with a famous cousin that I can guess donates a large amount of money to the school. My cousin and their spouse both went to Amherst.
If this will affect my chances at this school, by how much? And also, would it be helpful for my cousin to write a letter of recommendation to this school?
Nope. It’s not like your parents are donating a lot of money.
Nope, if anything it would be a distraction. If s/he cannot anything to your academics or EC that isn’t already covered by your other recs, it’s just a waste. AO’s have little time for “My cousin is a great kid” letters.
While a generalized letter may not help your application, if your cousin was able to put in a call to either the development office or sometimes the admissions office, your app may be “looked at carefully”- usually if an alumni with ties to the school requests special consideration for an app the college will at least remember that app and maybe take an extra glance over it.
I’m giving you the information an alumni of a top-ranked US college has told me about the app process. It may not be correct for every school, but IMO use the connections you have. College admissions is a big game, and you have to play.
You should definitely convey the info to the school. A letter can’t hurt. I suspect if you are a very strong candidate it may help. If you are a borderline candidate, it probably won’t help
Don’t leave us hangin’ like that! Tell us who the cousin is!
Is your cousin Albert II, Prince of Monaco?
MB: Dartmouths’ peer rec is unique – I know of no other institutions that want that. No school wants to be innundated w/superfluous LORs. None. I fully agree with SkiEurope. This naked name dropping is frankly considered quite gauche. Cousin relationships aren’t going to help you. Indeed, many schools don’t even consider grandparents.
It may make the OP memorable (hey, this is X’s cousin) for something that’s not negative. I suppose that’s a good thing if it reaches discussions. But while Amherst will note the relationship but it won’t breathe life into a dead app.
Apples and Oranges. The Dartmouth Peer Rec is a required rec, which the AO knows will be written by a kid who is not used to writing recs; any supplemental rec is just that - supplemental. If a supplemental rec does not add anything meaningful, it’s usually better to omit it. A thicker application is not a better application in most cases. I say this as a general opinion without any specific knowledge of Amherst. They may be unique in their legacy considerations, but I doubt it.
My kid mentioned cousins who went to Swarthmore, but it was part of her “Why Swarthmore?” essay – that was how she first heard about the school, and she admires their accomplishments after college.
If your cousin knows you well and.is willing to write a nice personalized letter it won’t hurt. But you do need to be academically qualified in your own right.
Cousin Dan Brown? Or Uhuru Kenyatta? C’mon, we won’t tell!
Cousin Drew Pinsky? Cousin Teller? Cousin pornstar Daphne Rosen? That last one really surprised me…
Have your cousin make a phone call to his development contact at Amherst. The development person will be able to provide more advice. I doubt that a letter from the cousin will do much good.
At most schools there is a firewall between admissions and development. I’m not sure how Amherst handles things but the development people are the best to ask. It is best coming directly from your Cousin and not you.
It’s not, actually. My D wrote one for her friend for Davidson last year.
OP said cousin’s spouse also went to Amherst so that should help narrow it down 
Why do I think cousin would not particularly appreciate this post?
Did you actually ask cousin if he/she is okay with you using his/her name in your app?
If you are close to your cousin and he/she knows you well and can write about you personally and specifically - AND - if you are otherwise well qualified for admission - then there is nothing wrong with having him/her send a letter on your behalf. Connections to a famous and generous alum do matter - they matter at every single private university in the nation. It isn’t going to get you in if you don’t belong, but it might get you plucked out of the large pile of qualified applicants.
If both of those things are not the case, then don’t do it.