I don't think it's that much of an overused topic. The exception would be talking about how much you love your family.. yes, that's probably been used before.
Go ahead and use that topic if you feel you can put yourself into it; that you can show the reader exactly who you are through that essay.
Keep in mind, though, that adcoms are older and more mature than you. If you come off as too much of a bleeding heart, or profess to have experienced 'true love' by age 17, know that some adults would likely see that as immature or a testament to your inexperience. By no means all adcoms, of course, but I know that I certainly would see that essay topic that way (but then again I am neither an adult or adcom, I just talk alot with them

).