Many marriage counselors are convinced that one of the greatest obstacles to a successful marriage is selfishness. To be selfish is to be excessively concerned with one's own welfare, advantage, or pleasure without regard for others.
Babies are notoriously selfish.
They are oblivious to anything but their own well-being. When they are uncomfortable they scream until someone relieves their discomfort. Their disposition is determined by the degree to which things go their way. Unfortunately, while many people mature physically and intellectually, their emotional growth lags far behind. They still view the world as they did when they were babies.