How to Count Generations in a Family Tree

Marc McDermott
First Published: | Updated: April 2, 2024

Arranging your family tree by generation can be quite a daunting task when you don’t know how, so how do you count generations in a family tree? 

The length of a family generation is generally measured by the age difference between parent and child. Generally, this is thought to be between 25 -30 years, so let’s look at how generations are counted.

Getting Started Counting Generations 

To start, you and your siblings and cousins make one generation, and your parents and their siblings from the next. Your grandparents and their siblings form the third generation, and so on.

The top-level of any family tree is the first generation, next down is their children, making up the second generation. This continues, with every successive generation becoming a number higher than the last.

Related: How Do Family Trees Work

What’s is a Generation?

With different definitions, genealogy books would describe them as family ties and kinship. In sociology, generation is a term used to try and understand the differences between groups of people. 

Generally speaking, these people are people born at a similar time. This means they will go through similar life stages that affect them in different ways, perhaps because they went through a recession in their 30’s or were too young to go to war but shared a similar experience with others of their generation. 

How Long Does A Generation Last?

Generations tend to last 25-30 years. The word generation is used rather loosely these days. Whether it is in pop culture or politics, it is generally referring to the age difference between people born and living at a similar time. 

These generations overlap at a certain point, but people born in the same decade will share experiences and memories different from those born in different decades. 

What Is A Great Grandparent?

The word “great” is used to describe each generation before your grandparents. So, your grandparents’ mother and father will be your great-grandmother and great-grandfather. 

Their parents become your great-great-grandmother and great great grandfather, and so it continues with every generation as you go back. 

What Is A Great Aunt or Uncle?

Your grandparents’ siblings are called “great aunts” and “great uncles.” This makes things a little complicated as it makes it difficult to distinguish between them and your great grandparents which are a different generation.

Nonetheless, if you know them well enough, it can be easier to put a face and a name to a person when organizing your family tree. 

Loose Connections 

Uncle and aunt are often used to describe a friend of the family. Perhaps they are one of your mother or father’s good friends and you have known them for all your life. These terms are usually used with affection and are not to be mistaken with the proper use mentioned above. 

Half brothers/ sisters/cousins or anyone related through marriage alone and not blood can often be described as brothers on official documents like wills. When drawing up your family tree or proper documents, it is important to take care and consider which relationships are genuine. 

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