If we consider the diagram above in respect of the three generations, i.e. grandparents, parents and children, we can see that the DNA, shown in colour under the relevant photograph, for each generation is completely different pattern from the others in the line. It is not only a mix from that of their parent, but shuffled around by recombination. If we consider anyone of the children’s DNA on the diagram it can be seen that the process is continuing, and that their DNA is completely unique to them when compared to their contemporaries. You will also note that it is already becoming difficult to trace back just three generations, therefore, by including more generations in a search it becomes virtually impossible. If, for example, we go back ten generations an individual will have up to 1,024 ancestors.

Not all of our DNA comes in the form of chromosomes; if we now consider the maternal line shown on the diagram, you will see blue arrows passing from mother to daughter. Inside the nucleolus of every cell, some DNA can also be found in structures known as mitochondria. They are small organelles, i.e. a specialized part of a cell that has its own function, which lie in the human cytoplasm of eukaryotic cells. Their primary purpose is to provide energy to the cell. Mitochondria are thought to be the vestigial remains of symbiotic bacteria that were able to live or move independently. This is evident because they contain a relatively small circular segment of mtDNA. An individual inherits their cytoplasm, which is a thick liquid residing between the cell membrane holding all the cell's internal sub-structures, called organelles that come exclusively from their mother, as these are derived from the ovum and not from the sperm.

An advantage of the mitochondrial is that it does not recombine between generations, and because all mtDNA is passed from mother to her child without recombination, we all descend from Mitochondrial Eve’s mtDNA by definition. The same applies to our Y-DNA that can be passed by a male only to his sons, which is shown as red arrows on the diagram, and in turn leads back to Y-chromosomal Adam. A very good explanation of the DNA testing process for genealogical purposes is provided on this site, so I will not cover it, but would recommend it to you. Instead I will now consider the results of our genealogical DNA test

The genealogical DNA test looks at the nucleotides, which are a sub-unit of DNA made of a molecule of sugar, a molecule of phosphoric acid, and a molecule called a base. These results do not have any medical value, but instead give genealogical information that can be compared to other participant’s results. Y-chromosomes have series of repeating nucleotides, known as short tandem repeats (STRs). The number of repetitions differs between males, however, a particular number of allele, which refers to a count of the number of repeats in an STR provide a genetic marker. Each STR has been assigned a unique name given by the HUGO nomenclature committee. When a mutation arises in a DNA molecule, the mutation is passed in a direct line of descent. These rare mutations are derived from copying mistakes, i.e. when the DNA is copied it is possible that a single mistake occurs in the DNA sequence, an outcome which is called a single nucleotide polymorphism (SNP). A change to a nucleotide in a DNA sequence is ideal for tracing or establishing genetic links. Each SNP is allocated a letter code and a number. The letter indicates the Institute or research team that identified it, and the number designates the order in which it was found. An STR test furnishes the personal haplotype, and the SNP the haplogroup.

A haplotype is the numbered result of a genealogical Y-DNA test. Each allele value has a distinctive frequency within a population. To explain this, the actual test results that established the link between Walter Kep and John Keep of Longmeadow, within the “East Midlands Keeps” are given below:

You will see that the above tables relate to a 67 marker test, and give the marker numbers on the blue row at the top of the table, under which are the assigned names on the yellow row, and the individual test results are given on the three red rows. The red rows are labeled accordingly: row “J” relates to John Keep of England, who can trace his line back to Walter Kep of Astwood, Buckinghamshire, who was born ca 1230; row “M” relates to Marcus Keep of America, who can demonstrate his line back to John Keep of Longmeadow, Massachusetts, who appeared in the town in 1660; and row “S” relates to Scott Keep of America, who can also follow his line back to John Keep of Longmeadow. The results are compared to other participant’s results to establish a genetic link. The more markers that are tested, the more reliable the results will be. A 12-marker test is not discriminating enough to provide conclusive results for a common surname, and because of that we ideally recommend any participant to take a 67 marker test, but are aware of the financial implications. A participant can take a lower number of markers test, and later upgrade to more.

If we consider the test result for John and Marcus we will see that they vary by one point at three marker locations, namely marker 43, marker 49/50, and marker 59, however, when we introduce Scott into the equation  the differences is only two, when compared to John, at markers 43, and  49/50. This demonstrates that a mutation has occurred at marker 58 in John Keep of Longmeadow’s descendants over the last nine generations. There are other mutations within the John Keep of Longmeadow’s descendants. The tables below relates to all the East Midland Keeps tested so far and shows that Marcus (M), his father Charles (C), brother Jonathan (Jo) and Paul (P) all have identical results in all 67 markers, and one different to Scott’s results (S). If we now look at Donald (D), a descendant of John Keep of Longmeadow, his marker 1 is different by one to all the others. Also Philip (Ph), another descendant of John Keep of Longmeadow, who took a 37 marker test, varies from the others by one at marker 13, therefore, in just nine generations there have been three mutations within this section of the family line.

USING DNA TO TRACE OUR ANCESTRY

We are often asked why our project’s DNA testing programme focuses only on tracing the male’s Y-chromosome (Y-DNA) parental line, and not the female mitochondrial DNA (mtDNA) maternal line. The reason is quiet simple; our project is a Keep surname study using genealogical DNA testing to determine the level of genetic relationship between individuals. It is common practice within Western Societies for a child to inherit their father’s surname, and for a woman to change her surname upon marriage to her husband's surname, so that is the simply reason why.