Visual Phasing With DNA

DNA is pretty cool. It allows us to learn a lot of things about ourselves as well as our ancestry and heritage.

The more we learn about DNA, the more we can apply it to many principles; health, genealogy, etc.

Now we have the concept of Visual Phasing with DNA.

What is Visual Phasing?

Visual Phasing was developed by Kathy Johnston, member of the International Society of Genetic Genealogy (ISOGG). Visual Phasing is the mapping of DNA (chromosomes) of two or more siblings to the four grandparents without the need to test their parents or grandparents.

Visual Phasing is the mapping of DNA (chromosomes) of two or more siblings to the four grandparents without the need to test their parents or grandparents.

The idea is that with enough siblings, you can recreate almost the entire genome set of their parents (and your four grandparents). Using this method, it can also help you determine which of the four grandparents’ lines you may share with other DNA matches from and other DNA testing resources.

Note: Visual phasing does not provide you with heritage information of your grandparents.

Performing Visual Phasing

Visual phasing utilizes the website GEDmatch is a website that analyzes and compares DNA using a variety of methods at the raw data level.

DNA results for each sibling must be downloaded into raw data from the original DNA testing site and uploaded to that website.

Click here for instructions on how to download your Raw DNA data and uploading it to

Using the One-to-One Compare tool, you’d compare sibling to sibling using the kit numbers that GEDmatch assigns after their data is uploaded. Working through this tool will give you tables for EACH chromosome similar to what you see below. DNA Updates

There are many steps to follow in analyzing the charts and data and requires trial and error, patience and time.

After additional research, there seems to be no template or wizard available online to input data and have the visual phasing completed automatically. GEDmatch is the tool.

How Accurate is it?

We know that true 100% results are only possible with testing but we also know that isn’t always possible. Visual phasing is giving us a window using charts of organized data to get what I would consider a fairly accurate idea of what the DNA of a set of grandparents would hold. I would say there is room for debate because as we often see with heritage numbers, surprises and abnormalities tend to come up in the results.

DNA can be tricky and confusing, especially when you start looking at the numbers at the chromosome level. I personally recommend reading the tutorials and guides written by the DNA professionals and seeking advice from the various genealogy DNA groups such as DNA Detectives on Facebook.

Where Can You Learn More?

Legacy Tree Genealogists guest-authored this blog that goes over the basics of genetic testing. It’s informative and very thorough in the details. It’s a great place to start for reviewing how genetic testing works.

The Genetic Genealogist has a complete, in-depth series that walks through every step of visual phasing. I’m working through this myself to further understand this concept.

Online Courses and Webinars

  1. The Virtual Institute of Genealogical Research offers an audio course for $69.99. Check it out here.
  2. Legacy Family Tree Webinars is hosting a seminar that will be broadcast live on October 29th, 2017 that will cover visual phasing in their Advanced Autosomal DNA Techniques used in Genetic Genealogy course. Find more information and register for FREE  here.