Autosomal DNA

Autosomal DNA

Alongside the allosomes (X and Y chromosomes), the autosomes make up the other twenty-two chromosome pairs in every cell in the human body. You inherit exactly 50% of your autosomal DNA from your mother and exactly 50% of your autosomal DNA from your father. Strangely, however, you do not inherit exactly 25% of your autosomal DNA from each of your four grandparents.

In each pair of autosomes, one comes from your mother and one comes from your father. They, in turn, got one of each of their pairs from their mother and the other from their father, but before passing the autosomes on, they are randomly recombined. The further back you go, the smaller the percentage of autosomal DNA you will have inherited from each individual in that generation. Because of the chance involved in determining which copy is inherited at each generation the amount of DNA you inherit from your different ancestors is very variable.

In the same way that you do not inherit exactly 25% of your autosomal DNA from your grandparents, you do not share exactly 50% of your autosomal DNA with siblings. This generally ranges from 38% to 62% and means that you can be genetically closer to one sibling than to another.

What can Autosomal DNA tell me?

Autosomes span over two billion base-pairs and make up a large percentage of your DNA. Autosomes carry many genes and are responsible for many of our traits - such as eye-colour, height, hair thickness and hair colour. For example, the MC1R (Melanocortin 1 Receptor) gene, the basis of our red-head test, is on Chromosome 16, encodes the receptor protein for MSH (Melanocyte-Stimulating Hormone) and controls melanogenesis - the production of melanin, affecting pigmentation.

As well as determining kinship between you and someone else - the percentage of shared DNA, Autosomal DNA can reveal your ethnic ancestry - the percentage of your DNA that has been inherited from different continents. We can see which pieces of which chromosomes have different ancestries, but it is not possible to know which ancestor you inherited which piece from.

Your Autosomal DNA

The All my Ancestry test describes a person’s overall ancestry, using many autosomal markers, rather than being focussed on one ancestral lineage. This is important as of course the Y chromosome and mtDNA only provide one part of the picture. All my Ancestry shows which of over 200 world populations you are most closely related to and estimates the proportion of your DNA that comes from seven different continental regions, as well as which blocks of DNA on your autosomes come from these continents. We are also developing more refined tests of relatedness in any ancestral line out to about fifth cousins.