We know the grandkids get one copy of each autosomal chromosome from each parent. We know those chromosomes are a recombined mixture of the DNA the parent inherited from the grandparents. When one maternal grandparent has tested, we know which segment of DNA the grandhild inherited from that grandparent. We also know the maternal DNA not shared wth the tested maternal grandparent came from the untested maternal grandparent. The same logic can be applied to the paternal line shared DNA.
For my grandkids where I have tested a grandparent on both the maternal and paternal side I made a chromosome map to add to their Christmas gifts. This is how I did it. You may add your own enhancements and make alternate color choices. I may make some of these text boxes a little snazzier, but you get the idea. If you have a good idea for an enhancement please let us know in the comments.
At Family Tree DNA I have access to the shared segment data and I like the shapes they use on the chromosome browser. You could do something similar with data from 23andMe or GEDmatch.com. It will look a little different, but would still be a unique educational gift.
- Login to grandchild's account
- Display chromosome browser (CB) with shared DNA to a maternal grandparent
- Grab a screenshot - SnagIt scrolls the web page to capture the entire CB display
- Display CB with shared DNA to a paternal grandparent
- Grab a screen shot as in step 3
- Display the Family Finder Matches list of the grandchild
- Divide the amount of total shared DNA between the grandchild and paternal grandparent by 68 to calculate the approximate percentage of DNA shared
- Subtract that shared percentage from 50 to calculate the percentage of DNA that was inherited from the other paternal grandparent
- Divide the amount of total shared DNA between the grandchild and maternal grandparent by 68 to calculate the approximate percentage of DNA shared
- Subtract that shared percentage from 50 to calculate the percentage of DNA that was inherited from the other maternal grandparent
In an image editor (I used SnagIt editor) make the changes below, frequently saving the image so nothing gets lost. You need to understand how to use an image editor to complete this part. Numbers on the image here correspond to the steps below. Click on the image to see a larger version.
[15 Dec 2016 addition: Next time I do this I think I will add the grandchild's name to the top as a title (maybe "Grandchild-name's DNA Map") instead of placing it in several smaller text boxes as shown here.]
- Open both screenshots and crop out the area around the CB display
- Double the canvas size of one of the images horizontally - I used the paternal CB screenshot and chose placement options so it would be on the left of the final image
- Copy the second image into the new canvas and visually align the CB displays so the same numbered chromosomes line up (both chromosomes 1 are horizontally aligned, and so on)
- Save the merged images to a new filename
- Choose a different color for each grandparent - I used red for paternal grandmother, blue for paternal grandfather, yellow for maternal grandmother, green for maternal grandfather
- On the paternal CB image, use color fill to change the color marking the shared DNA segments - my CB display is for the paternal grandmother so I changed the default shared DNA color used by Family Tree DNA to red
- On the paternal CB image, use color fill to change the navy color marking unshared segments to bright blue
- On the maternal CB image, use color fill to change the color marking the shared DNA segments - my CB display is for the maternal grandmother so I changed the default shared DNA color used by Family Tree DNA to gold
- On the maternal CB image, use color fill to change the navy color marking unshared segments to green
- Add a small gold circle to indicate the mtDNA that was inherited from the maternal grandmother and text box indicating the mtDNA is from Mom's Mother
- Add text boxes with the grandchild's name, a color key for the maternal / paternal lines, a color key for the grandmother / grandfather in each line
- Add a text box listing the percentage of DNA shared with each grandparent (calculated in steps 7 through 10 above
- Include whether X, Y, or mtDNA was inherited from that same grandparent
- Add a short summary of DNA inheritance
Print the resulting image on heavy paper used for certificates or awards; my paper has pretty gold curlicues in each corner. I selected to scale the image to leave borders on all edges so I could frame the image. On my printer, I have an option to print in draft, normal, or best mode. For these, I selected best mode to get the highest quality prinout my printer will make.
I framed the images and printed a second copy that would allow siblings to hold the papers next to each other to easily compare which DNA each inherited from each grandparent.
I am planning to add some additional explanatory text to send along with the images. And, of course, I will refer them to the appropriate pages in the copy of Genetic Genealogy in Practice for more details. After all, I did give a copy to all of my kids and some other family members once the book was in print. I might as well give them a reason to read it.
To cite this blog post:
Debbie Parker Wayne, "DNA Chromosome Map Poster for Grandkids," Deb's Delvings, 14 December 2016 (http://debsdelvings.blogspot.com/ : accessed [date]).
© 2016, Debbie Parker Wayne, Certified Genealogist®, All Rights Reserved