GDAT — Genealogical DNA Analysis Tool

Documentation for the Genealogical DNA Analysis Tool (GDAT), a desktop application that uses autosomal DNA to help research family trees. Choose a section below or read the overview.

Overview

Genealogical DNA Analysis Tool

Utilizing Autosomal DNA to Research Family Trees

What is Genealogical DNA analysis?

Genealogical DNA analysis is a method that can be used to trace a person's ancestry and family history using DNA samples. DNA, or deoxyribonucleic acid, is the genetic material that is found in the cells of all living organisms and carries the instructions for the development and function of the organism.

Genealogical DNA analysis involves analyzing specific regions of a person's DNA, known as markers, to identify patterns and similarities with other individuals. These patterns can provide information about a person's ancestry and family history. It can provide information about a person's heritage and help them connect with distant relatives. However, it is important to note that genealogical DNA analysis is not a perfect science, and the results may not be 100% accurate. It is also important to be aware of the potential ethical and privacy implications of DNA testing.

Introduction

The Genealogical DNA Analysis Tool (GDAT) is a DNAGedcom app that utilizes autosomal DNA to aid in the research of family trees. GDAT is specifically designed to analyze DNA data from genetic genealogy tests and help users identify their biological family members and ancestry.

GDAT provides several features for analyzing and visualizing DNA data, including triangulation, segment analysis, chromosome mapping, and ancestry estimation. It also offers various tools for comparing and filtering DNA matches, including surname searches, geographic searches, and pedigree analysis.

GDAT is available for download as a desktop application for Windows and Mac computers.

History and Purpose

GDAT was first released in January 2020 by Becky Mason Walker to replace its predecessors, Genome Mate and Genome Mate Pro. In June 2026, DNAGedcom took over the product to continue its legacy.

The purpose of GDAT is to collect in one place the data from genetic genealogy tests and provide the tools to conduct family tree research using DNA. It is specifically designed to store data locally in an encrypted database on the user's desktop computer, not on an internet server or the cloud. It provides a generic import process that allows users to import data obtained from the testing companies of their choice.

Types of Data Collected

• Profiles- data associated with the person or persons whose family history is being researched
• DNA Relatives - data imported from testing companies or input by users to track research
• DNA Segments - positions on chromosomes where a DNA relative is related to the Profile person
• Ahnentafels - profile and DNA relative family trees in ahnentafel format
• ICWs - DNA Relatives who are related to or in-common-with each other

Analysis Fundamentals

Core to the Genealogical DNA Analysis Tool functionality is identifying the Most Recent Common Ancestor (MRCA) between the profile person and associated relatives by reviewing relative ahnentafels and assigning a group name to each DNA segment. Group names are derived from the standard surnames of the MRCA's parents (i.e., Mason-Miller) and automatically assigned when the Profile person's ahnentafel is loaded.

Given the vagaries of surname spelling, a standard surname table is populated from the Profile's ahnentafel and can be modified or expanded by the user. All ahnentafels are assigned a standard surname from this table when loaded, providing the ability to assist in the identity of a relative's MRCA.

Once a known MRCA is identified, unknown relatives can be researched utilizing GDAT's built-in triangulation and mutually in-common-with (ICW) functions. Triangulation involves identifying 3 individuals descended from 3 different siblings of the same ancestral couple on the same DNA segment. One of these individuals being the Profile person.

For example, on chromosome 12 from base pair 24.5 to 76.2, a triangulation between Becky the profile person, DNA relative Jack and DNA relative Jill means there are DNA segments identified between Becky and Jack, Becky and Jill as well as Jack and Jill. This means Becky, Jack and Jill descend from the same ancestor.

Triangulations assist in identifying what branch of the Profile's family tree that all three are all related and can be used to identify previously unknown ancestors when shared ancestors are found in the DNA relative's ahnentafels. Mutually ICW is used when triangulation data is not available and is less reliable as it says that all three people are related but not necessarily on the same DNA segment.

Analysis Tools

The Genealogical DNA Analysis Tool app provides several tools that assist in finding Most Recent Common Ancestors (MRCA) of DNA relatives whose MRCA is unknown.

1. Segment MRCAs - lists the groups associated with the Profile person's ahnentafel and all DNA relatives with segment data having the same group name in their ahnentafels.
2. MRCA Associated Groups - lists the groups associated with the line of descent from all DNA relatives whose MRCA has been identified and any DNA relatives having these same group names in their ahnentafels.
3. ICW Profile Groups - lists the groups associated with the Profile person's ahnentafel and all DNA relatives having the same group name in their ahnentafels. Similar to item 1 but the DNA relative may or may not have segment data available.
4. Region Clusters - lists the geographical regions associated with the Profile person's ahnentafel and DNA relatives sharing those regions in their ahnentafels.

Features

The Genealogical DNA Analysis Tool app features include:

• Chromosome Browser - lists DNA relatives and their associated position on the chromosome along with a chromosome map of known MRCAs.
• Relative List - lists DNA relatives and a summary of their relationship to the Profile person.
• Ancestor List - displays the Profile person's ahnentafel.
• Segment Map - displays the MRCAs identified for all 23 chromosomes in graphical form.
• Relative pages - DNA relative specific information such as haplogroup, family group, email addresses, links to testing companies, research notes, ahnentafel, surname and region comparisons, and DNA segments.

Quick Links

1. Getting Started
2. Download
3. File Menu
4. Edit Menu
5. Import Data Menu
6. Relative Menu
7. Profile Menu
8. MRCA Menu
9. Utilities
10. Help
11. Asking for Help

If a menu is not displayed on the left hand side of the screen, clicking on the three horizontal lines in the top left hand corner will show the full menu.

DNAGedcom Extract

DNAGedcom Extract is a companion DNAGedcom tool that converts your DNAGedcom Client database into the CSV files GDAT imports — relatives, shared segments, In-Common-With data, and family trees from each DNA service. It's the bridge between the DNAGedcom Client and GDAT.

Learn more about DNAGedcom Extract →