Who's Quintin?

According to our son, his name is not Quintin, but Quin. He has responded to Tim and I calling him Quin for many months now, but any requests we might have for Quintin go unanswered. I wouldn't expect him to answer to a name he has heard only a handful of times, however it got me thinking. When will Quin ever know his full name if we never use it? (I am by no means suggesting that we start using it. I LOVE calling him Quin, and I am not sure I could stop if I wanted to!) The funny thing is that he will more often than not respond to Monkey. I guess that means that I call him that a bit too much. As for his full name, Quintin, I guess it will simply remain an optional name for when he is older, assuming we tell him that it is an option. As for now, why confuse him when he perfectly content responding to Quin or Monkey!