The “Exploring Family Trees” Tool

One of my favorite visualization tools for family trees is one I recently discovered at It is being developed by Brad Lyon and is currently in beta version.  This review is probably best read while you’re playing with the tool yourself.


Getting Started

When you first load the page, you will be asked to load a gedcom (tree file) from your computer or device. (All of the visualizations and calculations are done locally rather than on a server, so your privacy is protected.) You will then get an option to designate the root (home) person and, after a few seconds, another button to Show Validation Check Results. (The latter is also under Options on left.)


Data Validation Check

The data validation check searches your gedcom file for potential errors, which are listed in a popup window by category. Not all of these validation issues are necessarily problems … birth years, death years, and birth locations aren’t always known. (Birth location will come in handy, though … see below.) Some clearly need to be corrected, though, such as someone dying or having children before their own birth.

Clicking on a category (e.g., Marriage possibly too young, in the example below) gives you a list of the people in your tree who are affected. You can then sort by name, birth year, death year, or a comment describing the issue. Sorting by the comment lets you focus on the most egregious problems first. For example, a woman who married at age 15 might not be a true error, but someone who married at age 0 definitely is.  I even had a woman who married at age –1683! (That was typo. She married in 1890 but I entered 189.)

Another awesome feature of the validation check is that each person in the list is hot-linked to a Google search using name and birth/death years. That can sometimes lead you to additional online resources that will help to resolve the problem.

Because I maintain my tree at, I copy the error list to a spreadsheet file and use it to make corrections at Ancestry, then I upload a new gedcom to the Exploring Family Trees tool.


Navigating the Tree

Once you’re happy with your gedcom, you should get used to navigating within the visualization. This is what a basic tree looks like.  Men and women are color-coded and are positioned according to birth year.  The vertical axes show the birth years.

Hover your cursor over a node (dot) to get a pop-up with some information about that person, including their birth/death years and relationship to the root person. Click the dot to “pin” the window and to get options to view a straight-line path to the root person, to make that person the new root of an ancestor tree, or to make that person the root of a descendant tree. (You can also change the root person using the blue button at the top of the window.)

Under Options (blue button at top left), you can adjust the thickness and transparency of the pink and blue lines, show lifespan bars for each person, and show all labels (names of people). These features are best used on smaller trees, as they can overwhelm the appearance of large trees. This is what my father’s tree looks like with thicker lines, name labels, and my father’s great grandfather’s pop-up “pinned”. 


Country Flags and Annotations

Also under Options is a check box to “Show flag of birthplace country” for your ancestors. This gives a great visual of your family’s migration history. When only the continent is known, as opposed to a specific country, the tool shows a map outline. You can also add historical events using the “Add Annotation” button. Annotations can be a single date or a range, and you can slide the label from side to side to fit your tree.

Here’s what my father’s tree looks like with birthplaces flagged and with annotations for some of the events in the history of New Orleans, Louisiana, USA. The two couples on the far right were given birthplaces of “Europe” to show how that feature works.


Viewing Endogamous Trees

One of my favorite aspects of Exploring Family Trees is the ability to visualize the endogamy (cousin marriages) on my Cajun mother’s side. Cajuns are descended from French settlers in Acadia (now Nova Scotia, Canada). In 1755, the British forcibly deported about 10,000 Acadians, loading them onto ships bound for the British colonies, England, France, and elsewhere. The Acadians who eventually made their way to Louisiana became the Cajuns of today.

In both Acadia and Louisiana, the early settlers were isolated by geography, language, and religion. As a result, often the only marriageable partners were cousins of one degree or another. Carry on like this for 10 generations or more, and you end up with a tree that looks like this, where the swooshy lines mark ancestors who appear more than once in the tree:


Lines of Descent

One of my favorite uses of this tool is to visualize multiple lines of descent from a specific ancestor. Early in the Acadian settlement (around 1650), two brothers named Antoine and Étienne Hébert (pronounced AYE-bear) arrived. Their father’s name is unknown, but I am descended from him at least 17 times! (To make this image, I clicked on the node for “Unknown Hébert”.)  My grandfather’s parents were both Héberts, and even my grandmother could trace her lineage back to the progenitor Hébert at least three different ways.


Putting Multiple Features Together

For a really insightful peek into my mother’s family’s history, I can overlay her tree with country flags and historical annotations. This view puts the migrations — from France to what is now Canada, and then from Canada to Louisiana — into perspective. Also notable are the Spanish Canary Islanders who arrived in Louisiana in the 1780s and intermarried with the Acadians there.


Demographic Patterns

Hover your cursor over the purple shaded region along the left-side timeline to get a popup showing histograms for the number of children, lifespan, and age at first marriage for both the men and the women in the visible tree. I’m not sure whether this information has a genealogical use, but it’s really cool. You can drag the top and bottom of the purple region to bracket the time period, and then you can slide the purple region up and down to see patterns over time in family size, lifespan, and marriage age. For example, I expected to see a sharp decrease in lifespan during the Great Expulsion period, when thousands of Acadians died from disease or when the ships deporting them sank. I did, but I also saw a decrease in life span in the 50 years before the expulsion, which may have been due to crowding or higher disease prevalence as their contact with the outside world increased.

Knowing the birth rate over time for a specific family will give us a better estimate the number of potential cousins at different levels (i.e., how many 4th cousins, 5th cousins, etc.), which could, in turn, give us insight into how likely our triangulation groups are to reflect traceable relationships.


Sample Trees

Finally, the tool includes some sample trees that are fun to play around with. These trees are: British Monarchy, Descendants of Queen Victoria, Cleopatra, Charles II of Spain, Winston Churchill, Common Ancestor of All U.S. Presidents, and Lord of the Rings – Geronitus Took. You should definitely explore these on your own!



The Exploring Family Trees tool is still in beta version, so if you encounter problems or have feature suggestions, I encourage you to contact Brad Lyon.  His email is given under Options.


16 thoughts on “The “Exploring Family Trees” Tool”

  1. Really great, Leah! For obvious reasons, I love seeing your Hébert data, presented graphically. You are >seriously< Hébert! I only have one line–my Dad's. My main Hébert tree is over 30,000 people, so I'm guessing (?) that I'd have to try Brad Lyon's "Exploring" on my Mother's smaller tree. Looks like fun! Thanks for introducing it.

    1. Yes, I’m Hébert all over. Both of my grandfather’s parents were Héberts!

      Try the big tree and let me know if it loads.

  2. I uploaded my GEDCOM file and there is one connection where the line is black instead of pink or blue. Do you know what that indicates? I can’t seem to find it anywhere.

    As a side note, that is an unverified ancestor, so I would LOVE if it means that they don’t belong in the tree! Haha!

    1. Interesting! I don’t recall ever seeing a black line. You might try contacting the developer. Please let me know what you learn!

  3. This is really fantastic. I was complaining to my husband about the number of cross-overs I was finding in my tree, and how to chart them, and he sent this to me today.

    Do you have any idea what this does to your DNA connectivity to others in your family? At some point would you turn out being your own twin?

    1. I suspect you’re joking, but that’s exactly what happens with certain populations used in science labs: the individuals are so inbred that they’re essentially clones of one another. They’re useful for scientific experiments, because if you give one group of them Treatment A and another group Treatment B, you know that any differences in the outcome are due to the treatment and not to innate genetic differences.

      We don’t know of any human populations like that, though!

  4. hello, I like this tool a lot but since my gedcom has more than 12000 people, it doesn’t work anymore, what to do? thank you

    1. Hmmm, I suspect the issue is your computing power. The tool uses javascript, and all of the calculations take place on your end. My gedcom has 16k people, and the tool loads for me. If you have access to a different device, you might try that, or perhaps if you wait long enough it’ll work. If you’re getting an error message, contact the programmer. His email address is on this page:

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