How Do Family Trees Work?

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

Are you new to genealogy, and wondering how do family trees work? Don’t feel silly for asking- it’s actually a great question, and there are many important things to understand about family trees before beginning your research. A family tree is like a map that connects a person to their ancestors. It begins with yourself at the “trunk” of the tree, and as parents, grandparents, siblings, aunts, uncles, and cousins are added, the tree’s “branches” are created. A family tree is one of the most important genealogy tools you can use, so let’s learn more about them!

What is a family tree?

A family tree can be defined as “a chart representing family relationships in a conventional tree structure.” The charts are usually presented with the oldest generations at the top of the tree, and the youngest at the bottom- so the chart creates a “tree” shape as it narrows downwards to the most recent family groups. The use of a tree image to represent a particular family history dates back to medieval-era art, when artists attempted to illustrate the genealogy of Christ as described in the Bible; and to Renaissance times, when trees were used to illustrate the ancestry of Greek and Roman gods.  

The number of ancestors you have doubles with each generation. Everyone has 2 parents, 4 grandparents, 8 great-grandparents, 16 2nd great-grandparents, and so on. This means you could potentially have dozens, even hundreds, of branches in your family tree!  Some types of family trees only focus on direct ancestors- in other words, the tree only reflects your parents, grandparents, great-grandparents, and so forth- and excludes siblings, aunts, uncles and cousins. Other trees will add these extended family members into the picture (we will learn more about different types of family tree charts below). The more ancestors you discover, the bigger your family tree. 

How does a family tree work?

A family tree works as a chart that visually maps out an individual’s ancestral lineage, illustrating the relationships between family members over generations. Starting with a single person, referred to as the ‘root,’ the tree extends outward, showcasing direct and extended family connections through lines and branches. Each branch leads to a ‘leaf,’ representing an individual family member. These leaves can contain vital details about each person, such as their name, birth date, and relationship to others on the tree, presenting a detailed view of one’s familial history

Family trees are an essential part of genealogy research- they are the canvas on which you paint the “masterpiece” that is your family history. They provide a unique and easy-to-understand way of exhibiting your ancestry to the world. To a family historian, they also serve as a road map of your research progress, helping other genealogists determine family connections and paving the way for future research on the branches of your tree.

Family trees have been traditionally created by hand on paper charts and printed in books. Today, however, most people create their family trees digitally, using computer software like Family Tree Builder. Family trees can also be created within family history websites such as MyHeritage, Ancestry, or FamilySearch. Creating a digital tree offers many great benefits, including the ability to easily add and update information, and attach digitized images and records from various sources. Most importantly, a virtual family tree can be easily shared with family members, and preserved for future generations to enjoy and expand upon.

Family tree software and family tree websites allow users to download their information into what is called a Genealogical Data Communication, or GEDCOM, file. This is a special type of computer file that allows the user to move their family tree data between different programs. GEDCOM files were developed by the Church of Jesus Christ of Latter-Day Saints to aid genealogy researchers in building their family trees.

For example, Ancestry allows users to either upload a GEDCOM file from another program (to add a new tree to an Ancestry profile), or a user can export a current Ancestry tree as a GEDCOM file (to move a tree created in Ancestry to another program).

Digital family trees allow you to save digitized records to each ancestor on the tree. You can attach scanned photographs and documents to a family member’s profile, and save copies of records found online. You can personalize and customize your tree any way you like. Digital tree software and websites are quite sophisticated, and the technology is constantly changing, as genealogists demand new and better methods of building their family trees.

What do family trees look like?

While the tree-shaped chart may be the more common type, there are several different ways to display a family history. Researchers often choose a type based on their research goals. Here are some common family tree formats.

Traditional family tree

This traditional view displays family groups in a tree-shaped flow chart that includes siblings, aunts, uncles, and cousins- in other words, it does not exclude any family members. They are read from the bottom up, starting with the most recent ancestor, and moving upwards into more distant generations. When using a tree, it is important to understand cousin relationships– check out this article for tips on understanding how you are related to your more distant cousins. The National Genealogical Society is also one of many websites that offer free, helpful family relationship chart reference guides


This view displays a person’s direct ancestors only (parents, grandparents, great-grandparents, etc.). Instead of building upwards as in a tree view, pedigrees are often created left-to-right, with yourself on the left, your parents to the right, their parents to the right, their parents to the right, and so on. A pedigree will continue to expand outwards as more grandparent ancestors are added. 

A common numbering system used with pedigree charts is called Ahnentafel. The numbering starts with the main subject as 1, father as 2, mother as 3, paternal grandfather and grandmother as 4 and 5, maternal grandfather and grandmother as 6 and 7, and so on. With the Ahnentafel system, the number of any person’s father is double that person’s number (your father is 2, his father is 4), and the number of any person’s mother is double that person’s mother plus one (your mother is 3, her mother is 7). This makes it easy to track ancestor relationships.

Fan Chart

This type of tree also displays a person’s direct ancestors only, but instead of a left-to-right chart, the generations expand upwards in a fan or half-circle shape. The main subject is located in the innermost circle, with their parents displayed in a ring divided in two above the subject. Grandparents are displayed in the third ring above the parents, divided into four- and so on. These types of family trees are useful when working with certain types of DNA evidence, as they can help you track DNA inheritance from various ancestors.

Family Group Sheet

This type of record provides details on one particular “branch” of your family tree. On a family group sheet, one particular couple and their children can be documented and include space for details such as birth, marriage, and death. Group sheets can be useful for organizing data on a particular branch of the family tree, or for compiling information for a family history book. 

Family History Reports

Rather than introducing information in a tree format, a genealogist may decide to create a written narrative with details about a particular family branch and the records associated with them. The report can include a family tree chart, or the writer may list family generations by number within the narrative. This type of report can also be compiled into a book, or stand-alone.

To see examples of these and other family tree chart types, check out this article by Family Tree Magazine.

What is the order of a family tree?

Family trees usually begin with one particular research subject- this could be yourself, a parent, or another ancestor. This subject serves as the “trunk” of the tree. From there, you will build the tree upwards to reach the older generations of the subject. However, you may sometimes need to move in other directions during your research. This may occur if you are focusing on one particular tree branch, seeking the descendants of a particular ancestor- in this situation, you may be moving forward in time rather than backward. You may also be trying to connect cousins within the same generation, which may involve moving up, down, and sideways to determine where they fit in the tree! The shape of the family tree and the order in which generations are identified will not change, but it is very common for genealogists to “jump” from branch to branch as they continue their research.

Who should be included in a family tree

Who you should include in a tree may depend on your research goals. If a family historian is seeking to build a tree that includes all possible family members of a particular subject, they would seek out siblings, aunts, uncles and cousins as well as direct descendants. If they are only looking for direct ancestors, the focus would be on ancestral grandparents for a pedigree chart. However, genealogists often find that in order to identify grandparent ancestors, it is necessary to locate records for those additional family members. A best practice is to seek out records for as many family members as possible, so no important information is missed. Luckily, most family tree websites and programs allow you to change your tree “view” from pedigree to a full tree, so you do not have to choose one over the other. 

You may have family members who do not fit into the mold of husband, wife, and biological children. For example, you may have adopted cousins, half-aunts or uncles, or step-siblings. You may also have relatives who identify as LGBTQ+. Who is included in a family tree is up to the person creating it, but most genealogists decide to be inclusive of all family relationships. Each family member is an important part of the family’s story. Family tree-building websites and software are working to add more diverse and inclusive options for building family trees. For example, inclusive family history research has been a popular topic at the RootsTech conferences hosted by FamilySearch. 

How do I make a family tree? 

Start with what you know! You don’t need to have 10 generations of your family memorized in order to create a family tree! You can simply start with a piece of paper and write down all of the family members you remember: parents, grandparents, aunts, uncles, and cousins. Once you have all of the known information down, you can begin the research process, or start creating a digital tree. It is so easy to find family tree research assistance through family history websites and blogs, through step-by-step tutorials provided by family tree-maker software, or even on video sites such as YouTube. 

Additionally, most of the family tree-building websites allow you to create a tree for free (though you may need to pay for a membership to access additional records). Gone are the days where a family historian had to spend hours combing through a library or archive, simply to find one piece of information about their ancestors. A wealth of information is right at your fingertips, so there’s no reason not to start building your family tree today!  

So, are you ready to get started on your first family tree? Read our post, How to Make a Family Tree, for more information and inspiration. There’s no better time to “plant” your family tree’s roots and watch it grow!

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