DNA - summary - worth it?

[Glen in Tinsel Kni]

Would it be correct to say that as we only inherit 50% of each parent's DNA, some is going to be left behind?  A genealogical ancestor from a few generations back isn't necessarily a genetic ancestor, ie we may not have inherited any of their DNA.

Around 85% of 3rd cousins share dna and around 50% of fourth cousins, the percentages reduce the more distant the relationship. A good benchmark is matches to people where the common ancestor is 5-6 generations back with a lower return beyond that point but the number of distant relatives is much higher so there are still plenty of potential matches out there. 

[Sloe Gin]

Would it be correct to say that as we only inherit 50% of each parent's DNA, some is going to be left behind?  A genealogical ancestor from a few generations back isn't necessarily a genetic ancestor, ie we may not have inherited any of their DNA.

Around 85% of 3rd cousins share dna and around 50% of fourth cousins, the percentages reduce the more distant the relationship. A good benchmark is matches to people where the common ancestor is 5-6 generations back with a lower return beyond that point but the number of distant relatives is much higher so there are still plenty of potential matches out there.

What I was getting at is that I may not have any DNA from an ancestor 5 or 6 generations back.

[Biggles50]

I research my family tree for 15 years before taking a DNA test.

My whole Paternal side was wrong, Dad was not my Biological Father.

I now know who my Biological Father is and I now have a brand new pair of Siblings and all their family as blood relatives.

So yes, DNA will give you more family to include in your family tree.

But there can be skeletons unearthed so be prepared.

The thing is one DNA test is not really enough, ideally at least one First Cousin on each side should also test.  Then you can cross reference and validate ancestors by linking other DNA Cousins back to the MRCA (most recent common ancestors).

Finally, if you do proceed then do not be lulled into buying the cheapest, only buy from Ancestry as once you have worked through your DNA matches of note you can copy and upload the results of the test to other sites, but you cannot upload to Ancestry.  Plus Ancestry has by far the biggest number of DNA testers.

[Biggles50]

Would it be correct to say that as we only inherit 50% of each parent's DNA, some is going to be left behind?  A genealogical ancestor from a few generations back isn't necessarily a genetic ancestor, ie we may not have inherited any of their DNA.

Sort of a Yes (ish).

Each person is unique and the DNA process of inheritance is known as Recombination and it is random in the way it works.

Going back to a 4xGGP you may or may not inherit DNA but this is not necessarily true for each 4xGGP. If one does not inherit DNA from a 4xGGP then you do not inherit DNA from and of their forebears.  The image shows how it can work but do take note that each of us will have our own unique version of this inheritance tree and we may in fact inherit DNA from each of the forebears shown.

[Sloe Gin]

Great, thanks, that's what I thought.
And I suppose we don't all inherit the same bits of DNA, so it's feasible that we might not have a match with a distant cousin, but do have a match with another cousin.

[Biggles50]

Here is what some of us do.

We mark up our tree by either using a printed version of our Pedigree family Tree or add an DNA icon or image to the profile header of each person where we have validated that we have inherited some of their DNA.

Pretty soon we see where there are branches with no DNA Cousins who share DNA with us.

These are the ones to work on.

[Glen in Tinsel Kni]

Great, thanks, that's what I thought.
And I suppose we don't all inherit the same bits of DNA, so it's feasible that we might not have a match with a distant cousin, but do have a match with another cousin.

Correct, hence why siblings can have variations in their list of matches, whilst both will match around 85% of 3rd cousins it doesn't mean it's the same 85% for both of them. I have a batch of matches that span four generations of a branch but my half sibling only matches three generations.

A non dna tree can at best only ever accurately represent the details on the documents but that doesn't mean the details themselves accurately portray biology.

[Josephine]

Great, thanks, that's what I thought.
And I suppose we don't all inherit the same bits of DNA, so it's feasible that we might not have a match with a distant cousin, but do have a match with another cousin.

I've noticed this. My brother has DNA matches with some people that I don't have matches with, and vice versa, or he'll have a different percentage of a match; for example, he shares more DNA with the granddaughter of our great-grandmother's sister than I do.

[Ayashi]

That's where collaborating with other DNA matches is great. As long as you can find people willing to collaborate with you