It's amazing how easily we learn to say no. My son learned to shake his head from side to side (at seven
months!) every time he wanted me to know he did not want to eat.
The word No takes on a new meaning (or lack thereof) during the toddler years. According to a recent article in Redbook, kids hear the word No 400 times a day! That fact may explain why we develop a weird relationship with this word. We learn to ignore it as children. We dread hearing it during our teenage years. And in adulthood we avoid saying it.
Here's the permalink to an old post about How to Say No. It's time for a refresher.