People with empathy deficiency disorder, as some experts call it, lack a moral compass. They can’t distinguish between right and wrong, Dr. Riess said.

Research by Dr. Riess and her collaborators has shown that we are each born with a given number of neurons that participate in an empathetic response. But whether this potential to care appropriately for one’s fellow beings is realized or undermined is largely molded by early life experiences, starting at birth and continuing throughout childhood.

How, then, can a healthy degree of empathy be instilled in a child? “Empathy is a mutable trait, it can be taught,” Dr. Riess told me. “We’re all born with a certain endowment, but it can be dramatically up-regulated or down-regulated depending upon environmental factors,” especially, she said, by the examples set by a child’s caregivers.

Dr. Riess urges parents to be role models who show respect and caring for others: “Billy scraped his knee. Let’s go get a Band-Aid for him,” or “Mrs. Jones just came home from the hospital. Let’s take her some soup.”

Teachers and caregivers in child care and pre-K settings can foster empathy by acknowledging rather than dismissing a child’s distress or by bringing a toy or doll to comfort a child who is upset or injured. Libraries and bookstores are replete with stories in print and video that demonstrate the giving and receiving of empathy for children at different age levels. Among the many choices: “I Am Human,” “What’s Wrong with Timmy?” and a personal favorite, “Wonder,” which was also made into a popular movie last year.

Dr. Riess has vivid memories of how her parents demonstrated empathy, by bringing turkeys before Thanksgiving to the homes of people who had almost nothing. “Kids tend to focus on what they don’t have — this exposes them to people who have so much less and gives them the gift of being a giver.”

She told me of a program called Cradles to Crayons, in which volunteers package up donated items for children in need. The program, currently operating in Boston, Philadelphia and Chicago, provides essential items for needy children from birth through age 12.