Some DNA 101

This is one explanation which comes up frequently, among others, where I have about two minutes to send an answer, but I know the person needs a lot more than a few charts and paragraphs. But this is a good start, if you have tested and are floundering a bit.

For this minute, let’s say, I am not going to make any thoughts now about paper genealogy – people work their fingers to the bone. I am not saying genealogies are right or wrong – but this is about genetic matching and confirming matches and their common ancestors. I will say that DNA for genealogy upended the world of genealogy, we learn that there many mis-attributed parentages also called non-paternity events in ancestries. We are not concerned with those, this is about reading what you learn from DNA for genealogy testing.


This is a fan genealogy chart. The center circle is you. Those yellow dots, although not scientifically placed, are relatively accurate to represent that in the autosomal DNA test the at-DNA test the ftDNA called Family Finder test – the yellow dots are the people who we get DNA from. We might be 50/50 of our parents but for grandparents we might get 15% from one and 35 from the mate and for the other pair we might get 25/25 – to make up our 100 – so we miss a lot of people in autosomal.

You see by the time we get back to that 6th generation we miss lots of people and less and less any farther back.

You must pay attention to how many genes you share with a match – use any chart.

If you share 50 cMs with a match, a relationship chart will tell you what relationship that person must be to you based on the amount of shared genes. So if the amount of shared genes indicates that you are 3rd cousins, about – then no sense looking at 9th cousins in your tree to look for the match. I love Blaine Bettinger’s pages and he has the shared the cM project which is the go to guide for learning HOW two people are related. But you must follow these rules, this is a science part of it, with the only variation being some people are related two ways and then you must work in a different way to identify the common ancestors. There is writing about these relationship in other blogs, I will link below.


Version 4.0! March 2020 Update to the Shared cM Project!

Blaine Bettinger35 Comments

The Shared cM Project (ScP) is a collaborative data collection and analysis project created to understand the ranges of shared cM associated with various known relationships. The ScP has been very successful, with more than 60,000 submissions from amazing genealogists like YOU! To add your data, the Submission Portal is HERE. I am always collecting data, and hopefully the next update will have more than 100,000 submissions!

Men ONLY ONLY ONLY get y-dna from their father’s they do not not not get any X from their father – this is what makes the gender of men and women. Women get two Xs and men get a y from dad and an X from Mom.
So when a man sees matches marked as an X match – in their Family Finder results – they can know – barring genetic mutation which is rared than hens teeth – all the X gene dna matches that any man has came from Mom. This is a magnificent genealogy sorting tool.

It looks like this – in a X gene ancestry chart


The blue circle is a man this is the man’s, any man’s, x-DNA x-gene chart – of possible X ancestors. You see there is NOTHING from dad’s side. For instance is a man has a daughter – she will get some of that X gene the man got from his mother, and she will get some x from her mother also. But men get NO X and your sons, if any, get no X from their fathers.


This is a x-dna x-gene chart for females
When I fill out these charts – they MUST be in color and write in the names in pencil lightly – it is easy to make mistakes.

OK back to beginning


For autosomal dna the family finder all the relatives you were shown in 23andMe those matches are from all over your genetic ancestry.

That thin blue line on the left side drawn along the edge is what the y-DNA test covers – NOTHING else – it is a single strand of genetic fun carried from father to son. – No one else – no one of the ladies, none of the ladies father’s a single line of male y-DNA

On the right side of the chart is the red line, that is the maternal DNA mt-DNA and it also is only a single genetic reading that is a gene carried through mothers to their children.

All this DNA is read through any spit sample – you have all these different DNAs in yourself it is just what is tested.

To join the project – open your ftDNA Family Tree DNA page and from your main dashboard page see at the top PROJECTS and click – then the pop-up window will show JOIN PROJECT and click
When the next page opens you can search for us two ways – scroll down to DUAL projects and then under F search for 
French Broad River Families and click and then see JOIN button and click.
Or enter this name in search and ask it to search contains in name.
Again – if you go to your 23andme page you can see DOWN your page of any match – or ON DNA RELATIVES you will see this result of your haplogroup(s) and there you will have in one spot YOUR y-dna terminal SNP stated and also your mt-DNA stated.

The cover photo: “What is wrong with the right ancestors?” Sometimes we become attached to ancestors in genealogy research. But DNA for genealogy shows us we must remain true to the truth and DNA has helped us do that.

You will find the shared cMs chart down the page – Blaine Bettinger is the go to guy for all the latest and greatest in genetic genealogy.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s