Possible nightmare for the future re DNA tracing

[DevonCruwys]

Guy

I agree with you that in science nothing is ever proven, and there is always going to be much more to learn. Theory does in fact have a specific meaning in science:

http://lofalexandria.com/2013/01/fact-vs-theory-vs-law-vs-hypothesis-vs-proof/

However, there is reasonable certainty about many things so that we state them as facts.

While we can't ever prove that a child inherits 50% of its DNA from each of its parents, experiment after experiment has shown this to be the case. The hypothesis has also been confirmed by empirical data from thousands of genetic genealogists who have tested themselves and their parents and see that they too inherit 50% of their DNA from each of their parents.

I don't know all the technical details of the research on identical twins but distinguishing between the DNA of two identical twins is not something that the average genealogist is ever going to need to do.

Genetic genealogy combines genetics and genealogy. The science behind genetics is sound. There is no science behind genealogy. You might have your parents' marriage certificate which states the names of the two fathers but that doesn't prove that these people actually were their biological fathers. With DNA testing we now have a way to test hypotheses like this. You could for example test yourself and a first cousin who should have the same paternal grandfather as you to see if you have share the expected amount of DNA. If you do, then you can be reasonably confident that the information on the marriage certificate is correct.

[Guy Etchells]

Perhaps there is no science behind the way you do genealogy but there certainly is behind the way I carry out my research.

I study the reason behind the records I use to base my research on. I find out why they were created, what information is actually recorded, how it was recorded etc.
I also study the way the records have developed or changed throughout the centuries, both in what they record (and what they do not record) and how they are used.

When I have the information from the records I then experiment with the different combinations of that information to see if my theories hold water or if there are weaknesses in my assumptions. As I know many other genealogists do.
In the end I advance a theory; my tree which is the results of my research and experiments and is open to review by others to test, complying with another principle of science.

My tree is not fact, it is the collated results or my research based on a process of questioning the data recorded in the various historic records available. I do not try to prove the data to be true but try to prove the data to be false.
If I cannot prove the data to be false then I must accept it until further data comes to light.

Which if you look at the flow chart on the page you link to my methods fit very well into what is described there.
In fact that flow chart could actually describe genealogical research.

Definitions of Science

Oxford Dictionary:
The intellectual and practical activity encompassing the systematic study of the structure and behaviour of the physical and natural world through observation and experiment:

Cambridge Dictionary:
(knowledge from) the careful study of the structure and behaviour of the physical world, especially by watching, measuring, and doing experiments, and the development of theories to describe the results of these activities:

Note science does not provide proof of anything, science provides evidence or refutes evidence in exactly the way that good genealogical research does.

While we can't ever prove that a child inherits 50% of its DNA from each of its parents, experiment after experiment has shown this to be the case. The hypothesis has also been confirmed by empirical data from thousands of genetic genealogists who have tested themselves and their parents and see that they too inherit 50% of their DNA from each of their parents.

Whilst it is true that a child inherits 50% of their DNA from each parent it is not a simplistic as that. Much of the DNA a child inherits could come from either parent.
This means that after a couple of generations the DNA from one particular ancestor might no longer be found in the DNA of a person.

Science does not prove that one person is a parent but simply advances evidence that it is possible that a certain person could be the parent.

To say otherwise shows you do not understand the meaning of scientific research.
In fact I would go as far to say that to use DNA correctly one would have to not simply accept the analysed results of the DNA but question those results and try to prove them to be false.
But this part of science seems to be lost in your approach to DNA

Cheers
Guy

[DevonCruwys]

Guy

I approach my genealogy in just the same scientific way as you do.

Falsifiablity is one of the foundations of the scientific method but there comes a point when something is so well established that falsifiability isn't necessary. No one is wasting their time trying to falsify the hypothesis that the earth is round or that Mars exists or that grass is green.

I don't think you understand the basics of biology. Scientists have been observing human reproduction for decades by direct observation (eg of cell division under a microscope) so we know exactly how fertilisation takes place, how cells divide and how chromosomes are formed. Yes nature does sometimes play tricks on us and you will sometimes get, say, a female baby born with one X-chromosome instead of two (this is known as Turner's syndrome). But because we understand how the process works we can understand why this has happened, and it would in any case show up in any DNA test.

DNA evidence is just like any other evidence. You have to understand how it works and how to use it responsibly. It's the combination of DNA evidence with genealogical evidence that is often so powerful. On its own DNA doesn't tell you anything. Any good genealogist is going to want to take advantage of any record set going.

If you want to understand how DNA testing is used in combination with other evidence you might like to have a read of the Nature Communications paper on the identification of Richard III:

http://www.nature.com/ncomms/2014/141202/ncomms6631/full/ncomms6631.html
 

[Guy Etchells]

Guy

I approach my genealogy in just the same scientific way as you do.

Falsifiablity is one of the foundations of the scientific method but there comes a point when something is so well established that falsifiability isn't necessary. No one is wasting their time trying to falsify the hypothesis that the earth is round or that Mars exists or that grass is green.

I don't think you understand the basics of biology. Scientists have been observing human reproduction for decades by direct observation (eg of cell division under a microscope) so we know exactly how fertilisation takes place, how cells divide and how chromosomes are formed. Yes nature does sometimes play tricks on us and you will sometimes get, say, a female baby born with one X-chromosome instead of two (this is known as Turner's syndrome). But because we understand how the process works we can understand why this has happened, and it would in any case show up in any DNA test.

DNA evidence is just like any other evidence. You have to understand how it works and how to use it responsibly. It's the combination of DNA evidence with genealogical evidence that is often so powerful. On its own DNA doesn't tell you anything. Any good genealogist is going to want to take advantage of any record set going.

If you want to understand how DNA testing is used in combination with other evidence you might like to have a read of the Nature Communications paper on the identification of Richard III:

http://www.nature.com/ncomms/2014/141202/ncomms6631/full/ncomms6631.html
 

Guy

I approach my genealogy in just the same scientific way as you do.

Falsifiablity is one of the foundations of the scientific method but there comes a point when something is so well established that falsifiability isn't necessary. No one is wasting their time trying to falsify the hypothesis that the earth is round or that Mars exists or that grass is green.

Yet another misconception on your behalf the world is not round it is actually a spheriod, but don't let facts get in the way.

I don't think you understand the basics of biology. Scientists have been observing human reproduction for decades by direct observation (eg of cell division under a microscope) so we know exactly how fertilisation takes place, how cells divide and how chromosomes are formed. Yes nature does sometimes play tricks on us and you will sometimes get, say, a female baby born with one X-chromosome instead of two (this is known as Turner's syndrome). But because we understand how the process works we can understand why this has happened, and it would in any case show up in any DNA test.

Unfortuantely there are a number of things about biology and reproduction that science is not certain about, which is why many are still carrying on research into the subject. As those of us with open minds are happy to admit.

DNA evidence is just like any other evidence. You have to understand how it works and how to use it responsibly. It's the combination of DNA evidence with genealogical evidence that is often so powerful. On its own DNA doesn't tell you anything. Any good genealogist is going to want to take advantage of any record set going.

If you want to understand how DNA testing is used in combination with other evidence you might like to have a read of the Nature Communications paper on the identification of Richard III:

http://www.nature.com/ncomms/2014/141202/ncomms6631/full/ncomms6631.html
 

Thank you for including the url above, it was something I already know of due to family connection to the Manners family.

However none of this changes the point I have been making.
I repeat: I am not contesting the science I am contesting your terminology.

Cheers
Guy

[Redroger]

There are indeed many millions a DNA samples in police data bases; they can be discounted for Family History purposes are they are highly unlikely to ever be released!
I believe that we must then consider whether the sample DNA that we have of the entire human population is drawn at random. I believe that the sample is definitely skewed, and prominently skewed towards a predominently European population, and is therefore of little value as the 4 billion or more people who are of African and Asian etc. origin are seriously under represented.

[DevonCruwys]

The genetic genealogy bases certainly are skewed towards people of European origin and specifically towards Americans of European origin. However, the fact that there are few people of African and Asian origin is not going to be a problem unless you actually are African or Asian or have some African or Asian ancestry. It also depends on the type of test and who else has tested. Some surname projects are now very mature and have tested someone representing every single living line for the surname so anyone with these surnames who tests is going to find a match unless they're descended from an NPE or they're the last representative of their line.

[mike175]

Don't we all have some African ancestry? 

There seems a danger of genealogical DNA becoming a new religion. It's just another tool, of limited use to probably the majority of family history researchers. If anything, it seems better at disproving a family connection than otherwise. All that may change with scientific progress, and once there is a universal DNA database there will be no need for genealogy . . . or RootsChat  . . . and we'll all have to find another hobby. Don't imagine that will be soon though . . .

Mike.

[Redroger]

Thank you, to follow on; I am aware that many African Americans descended from slaves have surnames like Washington as that was the name of their original owner; however an African American with a white father and a black or mixed race mother should carry the same Y chromosome as other people with the same surname regardless of their colour; or am I missing somethin?

[DavidG02]

Thank you, to follow on; I am aware that many African Americans descended from slaves have surnames like Washington as that was the name of their original owner; however an African American with a white father and a black or mixed race mother should carry the same Y chromosome as other people with the same surname regardless of their colour; or am I missing somethin?

Without having had my morning coffee I will attempt an answer

In your example of white father/owner and black/mixed race , they should carry the Y chromosome of the progenitor. Surnames were adopted/given by slaves as to who owned them. The owner and the progenitor may not be the same person.

So in your example I would use surnames as a localiser and not for genetic disposition. Not every Jefferson is a Jefferson