Nearly every parent has watched a child refuse to share his or her toy. The child who is not sharing may even know that the fair and acceptable thing to do would be to share, but for some reason, he or she just can’t seem to resist grabbing the toy and holding on for dear life.

According to new research, an explanation for this behavior relates in part to an underdeveloped impulse control center in the brain. At birth, we are totally dependent and inherently selfish. As we grow, we figure out how to satisfy our own needs while also behaving in ways that are acceptable to others. But growing up is a process, and during this time children may learn and understand the concept of sharing yet sometimes still fail to act with fairness.

So, if your five- or six-year-old child has trouble sharing and “playing fair,” it may be that he or she does understand the concepts of sharing and fairness—concepts that you have probably reviewed on more than one occasion. Most likely, your child simply can’t resist the impulse to behave selfishly.

As your child continues to do the hard work of growing up, you can help by educating and setting a good example. Patient, recurring teaching and modeling will have a positive impact on the process and outcome.