My son wrote the “Grandparent” essay. Well make that the great-grandparent essay. It started with a humorous scene related to the funeral and went on to demonstrate the life-lessons learned from the great-grandparent with a couple of real examples of where my son used those lessons. It was engaging, funny and poignant and a real insight into my son and what he values. It (together with his accomplishments) earned him a likely letter to Harvard and a spot at his first-choice, where he chose to attend. It is not the topic but the delivery.
Orthodoxy runs deep. Last year I was traveling with a colleague from Yale. He had recently spent a week on a reservation helping Native American students navigate the college process, and he had been shocked by the degree to which the cliches and tropes of college essays had penetrated into their world. As he told me, the essays his students - who had lived vastly different lives than most mainstream applicants - were writing were indistinguishable from those written by applicants in southeastern Connecticut. They were composed of billowing clouds of "my global perspective" and "future potential as a leader" and "desire to leverage my education" to bllllllaurhfhasklafsafdghfalkasf.
Not just humor, but the overall tone of your application essay is remarkably important. It's also difficult to get right. When you are asked to write about your accomplishments, those 750 words on how great you are can make you sound like a braggart. Be careful to balance your pride in your achievements with humility and generosity towards others. You also want to avoid sounding like a whiner -- use your essay to show off your skills, not to explain the injustices that lead to your low math score or failure to graduate #1 in your class.