When the DNA says your parents are related

One of the first things I do when helping someone with their DNA results is to check if their parents are related. This can explain unusual patterns of matches, for example, all seemingly from one side. has a nice tool called “Are Your Parents Related” (AYPR) in the”Analyze Your Data” blue panel (middle right of page) which looks for places in the specified kit where the DNA is identical on both chromosome pairs, maternal and paternal. This happens when you inherit the same segment of DNA from each parent because they are related. We call this a homozygous run which is a fancy way of saying a stretch of identical DNA on both sides.

CeCe Moore specializes in helping people who make this discovery. Click here for the informational brochure she helped Brianne Kirkpatrick, genetic counselor, create. It includes where to get emotional support.

My goal is to help you figure out what the DNA means yourself. Can you deduce what the relationship of those parents is? Well a very simple rule of thumb is to multiply the shared DNA from AYPR tool by four and look up that new total at the DNA painter calculator for the possibilities. Then do further family DNA testing to confirm.

Why does this work? Let’s look at the numbers. Suppose your parents share 25% of their DNA. They will pass about half of that to you, so 12.5%. However only about half of that will be the same DNA so it will show up as about 6.25% on the AYPR tool.

Look at the image. The total is 215.3 when you multiply by 4 you get 861.2. You might look that up before you read on …

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Do my genes suggest I should drink less coffee?

Whenever a new study is published linking a specific gene or SNP to a particular trait or health risk I go rushing to my DNA results to see what I have, so I thought I would share how I do that.

My latest worry is my coffee drinking habit.

There are so many coffee and caffeine studies that I am totally confused about what I should be doing. One caveat is that most of these studies are far from comprehensive and all of them need to be taken with a grain of salt. Have they really factored out all the other possibilities that could cause this result? Let’s face it, it’s early days yet in understanding what specific genetic variants do.

Personally when I read one of these articles, the first thing I do is google that gene name to find the associated SNP’s “rs” number so that I can find that variant in my results. For example let’s look at  rs762551, a SNP involved in the metabolizing of coffee.

While it is easy to look up a gene or SNP if you have tested at 23andMe or GENOS by using their browse raw data functions, what if you have only tested at Or Family Tree DNA, which has deliberately chosen not to test health related SNPs?

It’s actually pretty easy to look up a SNP in your raw data if you have downloaded it.

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Using Spreadsheets

In recent discussions with a few of my genetic genealogy students, I discovered that many need some help with understanding how to use spreadsheets. So I went looking and found a series of excellent youtube videos that even taught me a few things. Here is the first one in the series.

He uses OpenOffice Calc which is free and happens to be the spreadsheet that I use.

The basic idea of a spreadsheet is to make a list of things that you want to keep track of, with the information about each of them listed next to them in columns. As you use it, you may decide to insert more columns, the things you are tracking for each, or more rows, the items you are interested in. You can also delete any of these and best of all, sort them.

For DNA tracking purposes, the only other important function to understand is formatting cells so that the numbers don’t surprise you by turning into dates or fractions when you do not want them to. Click here for a recent article claiming that 20% of scientific papers on genes contain gene name conversion errors because of this type of reformatting!

Personally I reformat the start and stop points to have commas so I can read the numbers more easily and make the centimorgans column (genetic distance) default to two decimal places so that they line up well. I also change the font to Arial.

Suppose you want to keep your match list in a spreadsheet. There are many articles on this blog that explain how to do that. Use the tag DNA spreadsheets to find them by clicking here –
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Using an ahnentafel and the DNArboretum tool

There is a new tool, a chrome add-on called DNArboretum, that will generate an ahnentafel ancestor list from a Family Tree DNA tree or from the old format 23andme tree (not myHeritage).

An ahnentafel is a very clever and condense way to show all your ancestors. When trying to match up with a DNA relative it is particularly useful since you can quickly scan their ahnentafel for places and names in common. Obviously it would be better to automate that comparison but with misspellings and Norwegian names that has not worked well for me. However it might work for you, so click here for my blog post about how to use automation to compare GEDcoms.


This is part of my ahnentafel as generated by DNArboretum from my tree at Family Tree DNA when logged into another account there. I clicked on my great grandmother Maren Wold and it bolded all her ancestors and descendants. Note that my parents are missing because they are marked private.

Sue Griffith of Genealogy Junkie has blogged in detail about how to install and use this tool at

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Organizing DNA results with your Genealogy:

While I have many spreadsheets that I use to analyze DNA results, what I also want is a field in my genealogy program where I can put simple DNA information like haplogroups, where the person tested, and the GEDmatch id number.

To my delight, the free online one world tree at has all those features. Plus you can see whom you might have gotten your X DNA from, as well as your Y and mtDNA ancestral lines. Another feature is that a person’s profile page shows the tests of relatives that are related by DNA. Here is my mother’s page:

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