A generation is an average period, usually about 20–30 years, during which children are born, grow up, mature, and begin having children. There are two main types of generations—biological and social—and they differ in how they define their priorities, values, and beliefs.
Generally, a generation expires when the last person born in that time frame dies. But that definition needs to be revised, especially regarding genealogical analysis.
Many of us think of generations as a social concept, groups of people born at roughly the same time with similar traits and experiences. Each generation is shown as a horizontal line on a family tree for genealogical purposes.
When exploring genealogy or studying familial timelines, individuals often ponder the question: How long is a generation? This inquiry seeks to understand the average duration between the birth of parents and the birth of their offspring, providing insights into the passage of time within family structures.
However, the term generation is also biological and groups offspring based on how far back they share a common ancestor. Scientists use this type of generation reckoning to make genetic predictions about the probability that a new mutation will occur in a DNA sequence.
Biological generation lengths vary between species but average around 25 years from a parent’s birth to their offspring’s birth. They were much shorter in earlier times when humans mated younger, and life expectancies were lower.
In the social sense, it is not uncommon for members of different generations to stereotype each other. For example, Millennials might be accused of being entitled, or Boomers of hogging resources, and those differences can lead to conflict in the workplace.
The definition of a generation is largely dependent on cultural and sociological factors. For example, the Silent Generation (those born between 1928 and 1945) was influenced by the Great Depression and World War II, leading them to value stability and security. Likewise, Gen Z was shaped by the Internet and smartphones and is known for its high levels of social activism.
A social generation is a group of people born around the same time and undergoing similar life experiences. These cohorts may have shared values, beliefs, and cultural norms and can be identified by various factors, including historical events, sociocultural shifts, technological advances, and economic conditions. Unlike biological generations, which can span up to 30 years, social generations are typically shorter.
As the first generation to experience significant societal changes as adults, Baby Boomers are characterized by their high civic engagement and advocacy for causes. The post-war “Silent Generation” is lauded for its work ethic and value of stability and security. A group of young Europeans posing for photographer Robert Capa became known as Generation X, but only after their parents had already begun to have children and started a new generation.
Millennials are often seen as technologically inclined, politically liberal, and socially aware, with a strong interest in philanthropy. Despite their relative youth, they have been through not one but two once-in-a-lifetime economic crises that have shaken their confidence in the future. The generation that follows them, Gen Z, has grown up in a world with multiple pandemics and a declining economy, driving them to focus on education and lifelong learning. Generation Z is also expected to be the most diverse generation in history.
Generational Cutoff Points
Family researchers often use generational cutoff points to help distinguish one age group from another. However, these designations can be misleading if the definition is not precise or consistent across sources.
Several factors can alter how long a generation lasts, including longer life expectancies and people delaying childbearing into later adulthood. Generational cutoff points also vary depending on whether you talk about a biological or social generation.
While biological generations are typically defined by parents’ ages when they had children, sociologists use different criteria for determining social generation boundaries. Generally, these are based on the birth years of the youngest members of the cohort. For example, Millennials include individuals born from 1981 to 1996, while Gen Z is the cohort that follows them.
While arbitrary, these generational cutoffs allow us to discuss similarities and differences within cohorts, including experiences with significant world events and technological changes. They also give us a framework for comparing cohorts in contemporary cultures to understand their shared values and attitudes. In addition, these definitions are helpful when examining family genealogy and DNA matches. However, these generational definitions aren’t generally applicable to populations throughout human history because population sizes and demographics have shifted so much. For this reason, it’s best to keep these terms in the context of contemporary research.
As a genealogist, it’s important to remember that the length of a generation can vary. It all depends on whether you look at a family or social generation.
When researching a genealogy, you should use official records such as birth, death, and marriage certificates to identify a specific generation of your ancestors. Combine these with newspaper articles and other historical documents to get a complete picture of your ancestors and their lives.
In the past, generations were defined by events and wars that marked their passage from one age to another. They included the Greatest Generation, dubbed that by TV news anchor Tom Brokaw for their selfless service and sacrifice in WWII. They also had Gen X, sometimes called the latchkey generation or middle child generation, since it was born during divorce rates and two-income households.
However, researchers have found that social events and trends can create a new generation. These include economic conditions, family structure, and access to education. For example, kids growing up in single-parent families tend to struggle more academically than their two-parent families peers. Additionally, many younger children are being raised by grandparents. This is a trend known as multigenerational living, and it has been linked to a higher incidence of mental health problems.