RootsChat.Com

Not a daft question at all Louisa, but it is quite a complex one. There are two sex chromosomes, referred to as X and Y. All males have one X chromosome, inherited from their mother, and one Y chromosome inherited from their father. Females have two X chromosomes, one inherited from their mother and one from their father.

So a child can only inherit an X chromosome from it's mother, because females don't have a Y chromosome. But it can inherit either an X or a Y chromosome from it's father, because a male has one of each type. Which chromosome it inherits from it's father determines it sex.

Since the Y chromosome is only passed down the male line it can be used to investigate the direct paternal line. That involves taking a separate and more expensive test than the more common autosomal tests offered by Ancestry and similar companies.

A different type of DNA called mitochondrial or mtDNA can be used in a similar way to investigate the female line. It is separate from the nuclear DNA tested for autosomal matching, and is passed down by a mother to all her children, both male and female, but only the female children can pass it on to their children. So it can be used to investigate the direct maternal line, but the line will be broken if a mother only has male children. mtDNA tests are also more expensive than autosomal tests.

I wouldn't recommend taking either a Y DNA or mtDNA test unless you have taken advice and understand what you might get from them and whether they will be of any help to you.

That's the brief answer I'm afraid. I don't have much more than a basic understanding of either Y DNA or mtDNA myself!

I hope that makes sense. I'm typing this on my phone since my PC failed yesterday, and it's not so easy to keep track of what I'm typing.

But as to other ethnicities that people may find coming up, very small %s below 5%, it could be anything from a gt gt gt grandparent or someone back in the early 1700s.

Or simply random noise with no factual basis, at very low percentages.

OK, I think I understand. FH will let you do that. You will end up with all descendants of the selected "root" ancestors, so not just a couple.

The easiest way to select them would be to add all the "starting" ancestors to a named list. The individuals required can be selected from a tree diagram by clicking each with the Ctrl key held down and copying them to a new named list first. Then just select the named list in the individual selection dialogue when creating the narrative report.

My highest Ancestry match has two children and both have been DNA tested.

Looking at and comparing the segment numbers and lengths there is no way that they appear to be related.

It is only though building a tree and getting the records found that they are found to be linked.

A Cousin of theirs also cannot be linked to them through the segment numbers and length.

Same with other DNA matches.

Going by the info Ancestry provides only allows you to go so far and making assumptions can lead to, well we all know where that can lead too.

Biggles, you are totally missing the point, which surprises me.

It is an additional tool in the armoury to help guide your research.

You make assumptions every time that you use a tool such as DNA Painter. Do you automatically declare the relationship between matches based on the highest relationship probability proposed by DNA Painter? Of course you don't, but you do use the probabilities to assess the most likely relationships and use that information to guide your research. Could the match fall within the 1% or lowest probability range that DNA Painter proposes? Yes, of course it could, otherwise the probability wouldn't exist. But would you decide to initially concentrate your research on that possibility in preference to the higher probabilities that the tool proposes? I very much doubt it, and at that point you are making educated or guided assumptions, which you use to direct the research that will hopefully find the proof you are looking for.

Assessing the number of matching segments and segment lengths is no different. It is an additional tool in the box to help guide you, more with lower level matches than the higher ones. It can help filter unknown matches of similar overall length more effectively, and guide your direction of research towards those more likely to be helpful to you with less effort.

When you look at your matches on Ancestry or elsewhere, do you make assumptions as to which matches are likely to be closer based on overall match lengths. Of course you do, or should. Does that information by itself tell you how you are related? Of course not, but you are guiding your research using assumptions based on educated principles. Again, absolutely no different.

If you still don't get it, I recommend (again) Tracing Your Ancestors Using DNA, edited by Graham S. Holton, Pen & Sword Books. It is an excellent read from the basics to more complex areas of DNA investgation, with each chapter written by a different expert in that particular field, and my copy is now very well worn and tattered from use as reference material.

Total cM and percentage shared are just two methods of expressing the same amount of shared DNA.

Dividing the total shared cM by 68 will give an approximate shared percentage. In this case 457/68 equals approximately 6.72% shared DNA. Either can be used in the DNA Painter Shared Project Tool. It's not necessary to know both.

Segment lengths and number of segments are also important at lower match lengths, where for instance a 30cM match over one segment is likely to be more significant that a 30cM match over say 4 segments, with a largest segment of 8cM. At the other extreme, with an overall match of 3385cM the longest segment and number of segments is pretty much immaterial to the conclusion.