DNA

[Suzy W]

Is DNA 100% certain?
I got a email regarding a lady being a 4th cousin.  Her side came from Cornwall then onto South America , and I have only one line from Cornwall then onto NZ, but no way can I find the missing link between us.
You would think going back 4 or 5 generations would be easy, oh no not my lot, they just had to make life a little hard.
My trouble is that one side of the family turned Kings evidence on some smugglers, so a quick name change and move somewhere else before the mob came after them.
But still no way of knowing how or where we connect.
Could my great great grannies who came to NZ lied about her family?  DNA has thrown me totally of course. 
Anyone else having trouble matching with other DNA matches?

[Guy Etchells]

How long is a piece of string?

Is DNA 100% certain?

This is one of those questions where any answer given is correct to some extent, it all depends on what you mean by the question.

I got a email regarding a lady being a 4th cousin.  Her side came from Cornwall then onto South America , and I have only one line from Cornwall then onto NZ, but no way can I find the missing link between us.

If the question is could DNA point to a possible link between the lady mentioned and your family? Yes it could.
Could DNA determine which ancestor was the link? That is more difficult to answer, it would depend on what tests were made on the DNA and whose DNA was tested amongst other variables.

You would think going back 4 or 5 generations would be easy, oh no not my lot, they just had to make life a little hard.
My trouble is that one side of the family turned Kings evidence on some smugglers, so a quick name change and move somewhere else before the mob came after them.
But still no way of knowing how or where we connect.
Could my great great grannies who came to NZ lied about her family?

This is possibly a higher probability than DNA proving very much at all.
Though to be fair she might only have repeated what she believed herself.

DNA has thrown me totally of course. 
Anyone else having trouble matching with other DNA matches?

From what I have read possibly 75% or higher have difficulty matching DNA accurately to others, quite a number have difficulty matching DNA to their own siblings and a few have difficulty matching DNA to "their" children.

If you view the development of DNA for family history in terms of the life cycle of a person it has just emerged from the womb and taken its first few breaths.
DNA in research is still developing though certain companies push it as if it can provide answers in truth it provides more questions than answers.
Give DNA development 10 or 20 years and we may find a number of today's assumptions are tomorrow's myths.

I believe that in the future DNA may be a useful tool in family history research, at present in most cases it is little more than an expensive toy.
E.G. As things stand today, it is assumed the a person's DNA is unique (with a possible few exceptions) to that individual.
However that assumption is based on a tiny sample of the world's population undergoing DNA testing, less than .05% of the world's population has been tested (and in that tiny sample duplicates have been found) therefore the claim that a person's DNA is unique cannot be proven.
To confuse the issue even more it has been shown that in some people there is more than one string of DNA in their body.
This means if a blood sample is taken from that person and a smear from say the mouth the resulting DNA will claim the results are from two separate people.

Cheers
Guy

[hdw]

Yes indeed, I've done the Family Finder DNA test with FTDNA and they have found me scores of partial matches who are allegedly something like 4th - remote cousin to me, but I haven't found a single "paper trail" connecting to me to any of them, even when we have some surnames in common. To be fair to the testing company - as the previous poster pointed out - the science is still in its infancy, and the companies are not yet able to pinpoint exactly how several people match each other.

I may say that I'm a pretty experienced amateur genealogist and I'm not fazed by the concept of 4th and 5th cousins. I've identified and met several people who are at that genetic distance from me - I come from a small Scottish fishing-village and we're all related to each other several times over.

Harry

[hurworth]

I don't think the science behind genealogical DNA testing is in its infancy at all, and it's not the role of the companies to work out how you are related.  Their job is to give you the data about where your chromosomes match (oh hang on......Ancestry doesn't have a chromosome browser....so if you test with them you won't have any idea)

Working out how you are related is up to the people managing the kits.  And for that to work you need accurate information from your matches, and you need a little understanding of statistics and biology. 

Often until some other relatives you have in common test you can't really tell where the connection is from.  That's not a problem with the science being in its infancy - it's just that there is not enough data to draw any conclusions until someone else tests.

Everyone doing testing has to remember at that every generation it is possible that the biological parents are not the same as the people on the paper trail.

We've been able to work out only a handful of people by looking at the tree so far and there are hundreds where the connection isn't obvious yet.

[Guy Etchells]

I don't think the science behind genealogical DNA testing is in its infancy at all, and it's not the role of the companies to work out how you are related.  Their job is to give you the data about where your chromosomes match (oh hang on......Ancestry doesn't have a chromosome browser....so if you test with them you won't have any idea)

Working out how you are related is up to the people managing the kits.  And for that to work you need accurate information from your matches, and you need a little understanding of statistics and biology. 

Often until some other relatives you have in common test you can't really tell where the connection is from.  That's not a problem with the science being in its infancy - it's just that there is not enough data to draw any conclusions until someone else tests.

Everyone doing testing has to remember at that every generation it is possible that the biological parents are not the same as the people on the paper trail.

We've been able to work out only a handful of people by looking at the tree so far and there are hundreds where the connection isn't obvious yet.

You are contradicting yourself in your reply regarding science in its infancy.

As the science develops more data becomes available as only a few people (in comparison to world population) have been tested that by definition shows a science in infancy.

Apart from the fact that the double helix was only first modelled in 1953 the fact that only a tiny proportion of the world’s population have had DNA tests done shows beyond doubt how little is actual fact and how much is assumed.
To put this better into context it took almost 100 years to map or model the DNA sequence from Mendel’s experiments on peas in the mid to late 19th century.

There used to be two main assumed facts about DNA one was the each person had a single specific DNA sequence, the second that each person’s DNA was unique to themselves.

The first fact has since been proven to be wrong some people have two completely separate DNA sequences in their bodies (Chimerism, this was only proved circa 2002).
The second fact may be disproved when a higher percentage of the world’s population have been tested. One the other hand this second fact may stand and may never be disproved.

Cheers
Guy

[hurworth]

Needing another person to test to give you more data doesn't mean that the science behind genealogical testing is in it's infancy.   It means you can't triangulate with two people.  You need three.  The third person provides more data.   That doesn't change the science.

The transplant community was aware of chimerism prior to 2002.