Famil Tree DNA Tests

 

FDA_microbiologist_prepares_DNA_samples_for_gel_electrophoresis_analysisNot so long ago we just never heard of DNA being used in everyday situations. And then suddenly every detective story on TV seemed to mention the suspect’s DNA being collected from the crime scene.

In the world of family history, DNA has also emerged into the main stream. Today if you want to prove that you are descended from a certain line then you may be able to use genetics to prove it.

But then there is the shorthand that is used that can confuse us a little. You may have heard people talking about “snips” or SNPs and STRs and wondered what this has to do with anything!

I will now attempt to explain what I myself was uncertain of until I attended one of the talks by an academic at last year’s Who Do You Think You Are? Live show and then found it explained again in chapter 12 of Anthony Adolph’s book Tracing Your Aristocratic Ancestors. Pen and Sword 2013

Chromosomes are made up of special proteins and DNA. DNA is composed of numerous base-pairs of nucleotides all arranged in a double-helix shape.

In every human cell there is a nucleus that contains twenty-two pairs of chromosomes that bear autosomal DNA and one pair that decides on the gender of the human. The two sets of chromosomes are reduced down to one in a process of myosis that produces eggs in females and sperm in males.

When a man and a woman have a child the male passes on the one set of his chromosomes and mixes with the female’s one set and so the next generation inherits from its parents.

It is a complex process that causes some slight changes or mutations which are known as genetic polymorphisms. Some of these mutations include single nucleotide polymorphisms which are often abbreviated to the letters SNPs.

A single tandem repeat is known as a STR.

SNPs and STRs do not, it is believed by the scientists who understand such things, carry any useful codes needed in the creation of ourselves, but they are there.

 

Individual genes have two or more possible states of being and these are usually referred to by the letters A or T and C or G.

An SNP is a change detected in a gene’s state of being from, say, A to G and you may see it being called a “unique event polymorphism”. Once a SNP has occurred it will now stay the same as it is passed down the generations and so you can see how this can act as a reliable marker for “deep ancestry” haplogroup testing.

 

So what about STRs?

 

They are a bit different. STRs occur in a different part of the chromosome and they are a series of multiple changes caused by the addition or subtraction of the number of base-pairs. So by counting these base-pairs the DNA company get to a numerical code. The great thing about these mutations is that they occur over a shorter time than the SNPs do and so they can change over shorter spans of generations.

 

Y-STRs are taken specifically from the male Y chromosome and are only passed down by the father, making the Y chromosome in any paternal line practically identical.

What we are presented with is two complementary sets of results: SNPs define a person’s haplogroup, or the group of people that share the same markers that can go back many thousand of years. The second is the smaller group of people that share the same STRs who are related to each other over the last couple of thousand years or less.

 

The second exception is mitochondrial DNA (mt-DNA). This is only passed down from a mother to her child, but which only her daughters will pass on. This means that we have a definite marker for the female-line, in other words the mother’s mother’s mother’s (and so on) family.

As we get closer to Christmas I have noticed that www.familytreedna.com are offering money off their packages for the holiday season. Do you know anyone who would like to have a present of a DNA test as it would seem to be a good time to buy?

Disclosure: Links are compensated affiliate links.

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Solving Family Tree Brick Walls

Many of us, researching our family trees, come up against the inevitable brick wall of forebears that don’t appear in the documents in the places where we expect to find them. Sometimes this can be because they have been recorded, but the spelling of the name differs each time an official makes an attempt to write it down.

 

Brick Wall buster tip 1. Can’t find anyone of that name? Try searching for variants as in the past spelling was not an exact science.

 

This week I was revisiting my ancestors who married in Gloucester and then went on to have a daughter baptised in Devon that eventually married a Thorn and so perpetuated the Thorn/Thorne line that leads down the tree to me.

One of the problems that I have with this branch is that they were not literate and had no idea of how to spell their surname. The evidence is in the parish register for Dartmouth, where I first pick up the female line. Both parties, to the marriage between the Thorns and the Sissells made their mark and did not sign. The register gives me the name of the father of the bride as James Sissell as he makes his mark as a witness.

Elizabeth Gardiner Thorn, as she becomes on her marriage, is eventually buried in Dartmouth and I can trace her in the census records and on her death certificate as having been my 2x great-grandmother, from the names of her family in these records. This is how I know that I am investigating the correct person.

Researching the christening of Elizabeth backwards, in the IGI on familysearch.org, I find that she was given the name of Elizabeth Gardiner Sissill and I also find the marriage of a James Sysal to a Sarah Gardiner in 1780 in St Nicholas’ church Gloucester.

St Nicholas', Gloucester Parish Records are at County Record Office

So now I have three versions of the spelling of their surname, Sissell, Sissill and Sysal, but it is only the beginning!

I found that Elizabeth had a brother, Thomas, though at his christening the vicar entered his surname as Sizzall in the parish registers.

Turning my attention to the deaths of Elizabeth’s parents – as any good family historian always will try to kill off their ancestors – I have only just had some luck after my visit to the Devon Family History Society’s Tree House in Exeter and to the County Record Office to look at the microfiche copies of parish records.

I had no idea if James and Sarah had remained in Dartmouth of whether they had moved on, or even back to Gloucester.

With the aid of the various printed booklets of transcripts, from the DFHS, I was able to identify a Sarah Sisell (the fifth version of the surname) buried on March the 17th 1831 in the St Saviour’s burials transcripts and a James Saissell (sixth version of the spelling) buried on the 5th January 1835 in St. Saviour’s Dartmouth. Then I could look at the relevant microfiche copy of the register, in the County Record Office, to confirm the transcript was correct.

Spelling was so much more fluid in our ancestor’s day. Indeed the words “Burials” “Marriages” and “Baptisms”, at the top of the pages in the very same register, changed form throughout the different years!

I can only assume that all the variants of the surname, as recorded above and said with a West Country accent, could have sounded much alike to the hapless vicar whose registers display the fact that spelling was not fixed, as it has become today.

For more tips to get your family tree back before 1837 in England & Wales I would recommend that you buy my CD How To Get Back Before 1837 in England & Wales.

Help Me Get Back Before 1873 in My English Family Tree

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