Here's why:
* No official policy: Colleges don't generally advertise or have policies favoring siblings of current students. Their admissions decisions are primarily based on merit and fit.
* Potential positive impact: Some colleges might view it as a positive sign, showing family loyalty and potentially indicating a good fit for the college's community. This is more likely to be a subconscious factor than an explicitly stated one.
* Potential negative impact (rare): In exceptionally competitive situations, having a sibling already enrolled might, in theory, *slightly* reduce the chances if the admissions committee needs to manage the number of students from the same family. This is very uncommon.
* Overall: The impact of having a sibling already enrolled is negligible compared to other factors like GPA, test scores, extracurricular activities, essays, and letters of recommendation.
In short, don't count on having a sibling at a college to significantly improve your odds. Focus on strengthening your application in all other areas.