What stage of development has the greatest amount of variation between individuals of the same age?

Early adolescence is characterized by the onset of puberty and significant physical, emotional, and social changes. During this stage, individuals experience a wide range of developmental changes due to the varying ages at which puberty occurs, along with different environmental, cultural, and personal factors that influence each adolescent's growth and behavior. As a result, this period sees tremendous variability in aspects such as physical development, cognitive functioning, emotional maturity, and social skills among peers.

In contrast, early childhood and late adolescence tend to show more uniformity in these developmental domains, as many biological and psychological changes are either still being established or have already stabilized by these stages. Adulthood, while it also encompasses a broad spectrum of experiences and lifestyles, often displays less variation in physiological development, which has generally completed by this time. Therefore, early adolescence stands out as the period with the greatest differences between individuals of the same age, making it a unique and pivotal time in human development.