I think this is a great topic for your PS. You were 5 years old at the time you came to America, so I wouldn't think the AdComm would hold you accountable for those actions, as much as your parents (if anyone). However, I agree...now that you have gained citizenship I think you're in the clear.
This story would be a great way to get across to the committee who you are as a person and where you came from, while at the same time providing a great story. I would also tell some of it as a narrative, not only using first-person: "The car began to head for the Mexican border and was almost there, when a man shouted to duck down behind the seats." (For Ex.)