"The Invisible History of the Human Race" by Christine Kenneally

Completed on 2nd of April 2016.

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Notes:

Inside each cell of each person is a massive library of DNA, 3 billion base pairs that have been passed down to us.

Women have 2 X chromosomes, whilst men have one X and one Y chromosome. The Y chromosome is passed down from father to son as is. The X chromosome is always from the mother. In case when something goes wrong with the copying process there are differences between the Y of a father and that of his son.

Mothers have their own genetic markers too, but they aren’t part of the human genome. Rather, they are found in mitochondria, which float in the space between the bubble of a cell nucleus and its outer layer. Mitochondria have their own DNA, which is passed down from mothers to their children in the ovum.

Apart from the Y and X chromosomes, the rest of the genome is called the autosome. These 22 chromosome pairs are all the ones that get recombined before they are passed on.

Three major companies are involved in testing DNA: 23andMe, Family Tree DNA and Ancestry DNA.