Parents ann and frank are convinced that their 2-week-old baby devin smiles at them to engage them in parent-child interactions. on average, at what age do children begin to exhibit social smiles?

Baby's typically exhibit "social smiles" when they are about 2 to 3 months old. 

During the first few weeks of your baby's life (0-6 weeks), a baby will typically show fleeting smiles, even in their sleep. These smiles, however, are called "reflex smiles" and they are innate and a part of a reflex action or survival instinct believed to keep them safer as the smiles make the babies more appealing. 

From 6-8 weeks, a baby will show responsive smiles, as a reaction to pleasurable sensations (e.g. cuddles, voices, faces) instead of as a social response. 

By the time a baby is 2 to 3 months old, he/she will exhibit social smiles as a way to connect with you. He/she learns to express himself and learns that his/her smiles can draw a reaction from other people (especially his/her parents) too!