This guide is about how DNA that is used, such as by those in our guide to find the best ancestry dna test kit.  It is written in a clear and simple step by step manner, so that it is easy to understand.

To be frank most genetic ancestry testing kits, just give you the results and you do not even have to worry about how it did it.  A bit like how to drive a car, you do not need to be an engineer that understands about engines, electricals and so on.

When using anncestry dna test kit for your needs and get the most out of it, you just need to know the different kinds of tests which can be easily learned.  Also the guide will tell you the features of each one, to get the one that best meets your needs.

However if you are reading this, you probably love this stuff and so here we go!

This has all been written in an easy to understand and way, so please no worries about difficult and horrible school stuff.  Please just take it step by step and you can do it.

We are made of cells.  When we start off there is just the sperm from the father and egg from the mother, these make the first cell.  These then divide and when they divide, the DNA data is also in every single new cell that is created.

The genetic code of information is part of each new cell.  This is for the how the cells will grow and work.

These cells are controlled from the genetic code we have.  For example our genes tell us which hair color we will have.

What is dna made up of

We are going to start from the smallest and then work  through the building blocks, until we have the whole thing.  It may not make sense until you get to the end.

Please do not worry if you do not understand things along the way. Once you have got to the end, you can always go back.

Just like any story, it may not make sense until you have gotten to the end.

The word DNA is short for deoxyribonucleic acid.

A bit of the deoxyribonucleic acid has genes in, these are the segments that are the plans to create RNA (ribonucleic acid) or a protein.

1, Nucleaotides:

These are what DNA is made out of.  They are molecules.

They are made out of a sugar group, a nitrogen base and a sugar.

There are 4 types of nitrogen bases that that pair up.  This is what we will be looking at most, because the order of these in the cells are the genetic codes.  What we term DNA.

Adenine, cytosine, guanine and thymine.

Each DNA molecule is made up of a string of millions of these smaller units.

These strings are in pairs and make up a single double helix structure called a chromosome.  These chromosomes are in the center of each cell.  This is what the control center of each cell is.


Summary so far: DNA is a code, made from the order of adenine, cytosine, guanine and thymine inside the cells.   They are put in strings called chromosomes.


2, DNA

DNA molecules are made out of millions of nucleaotides, all entwined in strings.

A standard human cell has 92 DNA molecules in.


3, Gene

On each of these strands are chromosomes.  Each one has the code for a different thing, for that person.


4, Chromosome molecule:

A double helix of two of these DNA molecules

As there are 92 DNA molecules and they are put in pairs.

There are 46 strands of chomosomes made from this.


5, Chromosome pair

Each chromosome molecule is made into a pair.

Two chromosomes that go together

So  as there are 46 chromosomes to make into pairs, there are now 23 chromosome pairs.


So to summarise:

There are millions of nucleaotides.

These nucleaotides are put on 92 DNA strands.

This makes 46 pairs of these DNA strands, which are now called chromosomes.

These 46 chromosomes are put into pairs, making 23 chromosome pairs.


The maths is:

92 strands put into pairs make 46 chromosomes.

46 chromosomes put into pairs, makes 23 chromosome pairs.


One small thing,  One of the 23 chromosome pairs is Mitochondrial DNA  (mtDNA),  is seen as a ring, rather than a strand.  This is because it is a sex chromosome, the other are not and called AutoSomal.

So in some tests it is looked at separately to the 22 others.


Scientists are also finding more and more bits of the DNA that do not produce proteins or RNA.  They are secondary functions which are not genetic code.


There are more DNA than this, because hundreds of thousands of copies of these are in the mitochondria outside the nucleus where the 23 pairs above are.  Mitochondrial provide the power and energy that our cells need and is also used in some ancestry dna testing kits.

It looks like a small circle, rather than a strand.



How it works in the laboratory


A karyotype is all chromosome pairs, put out in order of the longest to the shortest.  They then number each one.

The photo of this is what is called the kayyotype.

To make the chromosome pairs more visible in the photo, the scientists stain them.

Then things are done digitally.  The computer orders them into a numbered order.

In the picture wil be

  • 22 chromosome pairs
  • 1 pair of sex chromosomes
  • Rings of MtDNA

Genetic geneologists just do 4 types of DNA testing.



For ancestry genetics, there are 4 things that are looked at:

Some just do the AutoSomal  test, some do more tests.  The page for the best ancestry dna test kit reviews, shows what each of them does.

1, AutoSomal DNA (atDNA):

This looks at the 22 Chromsome pairs that are not the sex one.

This is the one that all ancestry, heritage and ethnicity dna testing kits look at, because it can match to specific people and gives the most information.

This is because it comes from both parents, one copy from the father and one from the mother.  So it gives information about both sides of the famly.


2,  Y-Chromosomal DNA testing:

There are two chromosomes that cause gender, the X and the Y Chromosome.

Women have two X chromosomes and men have a Y and an X.


Men = YX

Women = XX

A son gets his Y chromosome from his father and that is how it is passed down.

So this test only works for males, as only they get the Y chromosome.  One way for a women to get the same results from the test, is if can get a brother, father, or uncle on father’s side to do the test.

It tends to be done if the ancestry DNA test kit,  looks further back than 5 generations, because it changes less with each generation.


3, X Chromsomal DNA:

This is just done by the more expensive ancestry dna testing kits.

The X chromosome is the other one that determine’s a person’s sex, the other of course being the Y above.

A woman gets one X from their mother the other from their father.

Men just get one X chromosome from their mother.

So for men it only says about their mother’s side of the family, because they get the X from their mother and not their father.

For women it shows both, as they get X from both their mother and their father.


4, Mitochondrial DNA (mtDNA):

This is the small circular one that is not in the cell’s nucleus.  It is where the cell gets it’s energy from.

Interestingly a child gets it from their mother.

They get this whether they are a male or female, so both can be tested.

It also tends also be done if an ancestry dna test kit looks back further than 5 generations.

The choice if which you use will depend on your aims and budget.

As we will see from this site though, it is not just about the different type of tests, it is also about how well the data is used.   For example how many samples the ancestry dna test kit company has to compare your results against, to get to the conclusions for the report it produces for you.