The Family Cycle
Infancy is categorized as lasting from birth through the first year of life.
Childhood takes place between ages 1 to 10.
Adolescence takes place between ages 12 and 18 and is a critical turning point because it is when puberty takes place.
Adulthood is the longest stage and normally lasts from age 18 through old age. While there might be smaller psychological or culturally defined stages, adulthood is when human beings are fully grown and must provide entirely for themselves using the skills they learned throughout the first life stages