A generation is generally defined as the average time between the birth of parents and the birth of their children. In human populations, this typically ranges from about 20 to 30 years, though there is variation depending on gender, society, and historical period
. Key points about generation length:
- The commonly cited average generation time is around 25 years, often used for genealogical and historical purposes
- Some genetic and demographic studies suggest that female generation times tend to be around 30 years, while male generation times can be longer, around 30-35 years, due to men often fathering children at older ages
- Historically, generation lengths were shorter when people married and had children younger, but modern trends toward later parenthood have increased average generation times
- Social or cultural generations (like Millennials, Gen X, Gen Z) are often defined by birth cohorts spanning roughly 15 to 20 years, which differs from biological generation time
In summary, while the biological generation length is roughly 20-30 years, the concept of a generation can vary depending on context-biological, genealogical, or sociological-with social generations often lasting about 15-20 years and family generations closer to 25-30 years
