Chromosome mapping

Some genetic genealogists use chromosome mapping–the comparison of shared chromosomes with your known DNA matches—to assign specific pieces of your DNA to specific ancestors.

There are many tools you can use for chromosome mapping. Here are some options to try.

Chromosome mapping tools to try

DNA Painter

DNA Painter is a great free online resource for chromosome mapping. You will need to register on the site, then create DNA profiles and fill them with data from chromosome comparisons with your matches on 23andMe, MyHeritage, Family Tree DNA or GEDmatch. Here’s my tutorial on chromosome mapping at DNA Painter. Once you’ve completed the process, DNA Painter will color code the chromosome graphics to correspond to genetic strands that belong to your ancestors:

Kitty Cooper’s Chromosome Mapper

Genetic genealogist Kitty Cooper developed an Ancestor Chromosome Mapper that many people have used and loved. However, if you click through to her website, you’ll see that Kitty’s now referring people to DNA Painter instead of her own.

Dave Bindon’s spreadsheet

Genetic genealogist Dave Bindon has also developed a spreadsheet for this purpose (way to go, Dave!). Due to his very generous nature, he has agreed to share it with the genetic genealogy community. Click on the boxes below to automatically download the spreadsheet and instructions:

Genome Mate Pro

Tech-savvy genetic genealogists may enjoy playing with the Genealogical DNA Analysis Tool (GDAT) (formerly known as Genome Mate Pro), an app to help manage autosomal DNA data. You can gather data from multiple testing kits from 23andMe, AncestryDNA, GEDmatch and Family Tree DNA. The app does chromosome mapping, triangulation and “in common with” grouping, and shows ancestors on your X-inheritance path. You can even import genealogical data! This app is available for the Windows, Mac and Linux desktop platforms.

On using chromosome mapping for genealogy

Many genetic genealogists are using chromosome mapping to help them determine how an unknown match is related to them. For example, if you know that a particular section of chromosome 17 is from your paternal grandmother, and you have a match sharing that section with you, then you would surmise that match is also related to you on that line.

However, to even figure out the origin of that specific part of chromosome 17, you have to be matching a cousin (let’s say it’s Dave) that you know is related to her. Save yourself the trouble of figuring out which chromosome you are sharing with your new match, and just use the shared matches tool found at every company to see that your new match is also matching Dave, which means she is related to you through your paternal grandmother.

There are very specific, fairly rare instances when just knowing the DNA is shared with Dave is not enough (like in cases of endogamy, pedigree collapse, etc) but for most of you, it is enough.

Read more on chromosome mapping—including methodology, cautions and resources—at the ISOGG wiki.

Does chromosome mapping sound like fun but a little over your head? Schedule a coaching session with Your DNA Guide. We can get you started!