What do you think influences a child’s/adolescent’s development?

There are three major factors that influence human development.

The first is the common genetic inheritance of the species Homo sapiens. The general outline of development is contained in every human being’s DNA. From conception through birth and beyond, physiological development happens according to a common human blueprint. Synaptic development, myelination, and lateralization all occur on a schedule programmed into our common DNA (Bee & Boyd, 2007, p. 93-99). While experts cannot trace the exact physiological roots of behavioral development, it is clear that the increasing capacity of children parallels the increasing sophistication of the physiology of the body and brain.

The second factor is the specific genetic inheritance of individual human beings. The forty-six chromosomes Influence everything from appearance to physical abilities to personality to mental abilities. This unique individual genetic inheritance creates and defines each living entity in its raw form.

However, neither our common or specific genetic inheritance is determinant. The third influence is environment. As described by Aslin’s Models of Development (Bee & Boyd, 2007, p. 9), different aspects of development are differently sensitive to environment. Some, like vision or language, have critical or at least highly sensitive periods where some base level of stimulus is essential to proper future functioning. Other aspects, like IQ, result from a complex interaction of different genetic and environmental influences. However, it is clear that proper diet, positive stimulation, loving attention, and emotional and physical safety provide significant modifiers to the core genetic programming.

Imagine that a human baby is a football thrown for a deep pass. The common genetic inheritance is the physical laws operating on the football: gravity, friction, rotational forces, etc. The specific inheritance is the football itself: the shape, the weight, the color, the material, the stitches, the individual variations of this particular football. The environment is its passage through the air to its reception: humidity, wind, temperature and, most importantly, the human(s) at the far end, adjusting their behavior to the flight of the ball to provide a safe landing into loving arms.

Reference

Bee, H., & Boyd, B. (2007). The developing child (11th ed.). Boston, MA: Pearson Education, Inc.