The patrilineal genographic family tree is mapped out through markers in the Y-chromosome DNA. Since only males have Y-chromosomes, Y-DNA, unlike most DNA, is inherited from one parent only – the father. This means that every male’s Y-DNA has exactly the same sequence of nucleotides as his father and, consequently, to his father's father and so on. However, on the very rare occasions where a mutation occurs, a male child’s Y-DNA will be different to his father’s at one nucleotide, e.g. a G in the sequence might become an A. If that child has male children, this mutation will be passed on to them, and if they in turn have male children, they will pass it on to them and so on. Any of the descendants of the original male bearing the mutation who are descended along a continuously male line will carry the same mutation. Hence, it can be determined from the presence of that particular mutation in any male’s Y-DNA sequence that they share that same male individual in whom the mutation first occurred as a common ancestor along their paternal line of descent.

Each time a mutation occurs, a new branch or subbranch (haplogroup or subclade) is formed in the patrilineal genographic family tree, with all bearers of the mutation belonging to the same branch. By tracking the geographic locations of these haplogroups, particularly among indigenous populations, the shared ancestry of different population groups can be determined and the long-term patterns of human migration estimated.

DNA testing shows that Kai's Y-chromosome bears the mutation known as P19 which is one of three makers definitive of haplogroup I. This haplogroup is found almost exclusively among European populations, accounting for 18% of paternal lineages, with the highest frequencies found in the Balkans and Scandinavia. It is also particularly common in southeast Europe, particularly among Slavic-speaking populations. Its frequency is lower in western Europe, though it is still quite common, including in the British Isles.

All non-African populations share a common ancestor known as the “Eurasian Adam” who lived 31,000 to 79,000 years ago, probably around the region of Ethiopia or Sudan. He was the first to carry the genetic marker known as M168. Some Africans and all non-Africans share this marker.

Some of his descendants, defined by the marker M130 (haplogroup C) and others defined by the marker M174 (haplogroup D) left Africa following a southern Asian coastal migration route around 50,000 years ago. Kai’s patrilineal ancestors left in a later migration out of Africa to the Middle East, about 45,000 years ago. It is defined by the marker M89 (haplogroup F) which arose in Africa or the Middle East around that time. More than 90% of non-Africans belong to subbranches of this haplogroup.

Most of this haplogroup F migrated west through Iran. Most of the population of Europe comes from those of this group who had migrated to the steppes of central Asia, eventually migrating into Europe and branching into subgroups R1a (dominant in Eastern Europe) and R1b (dominant in Western Europe).

Kai’s ancestors, however, remained in the Middle East for longer where the markers M170, M258 and P19 which define haplogroup I, appeared around 20,000 years ago. They then migrated into southeast Europe, where haplogroup I is most common. Their migration parallels the development of the archaeological culture known as the Gravettian culture.

Kai also has the marker M223 which originated from a man probably living in the region of around southern Germany about 14,000 to 18,000 years ago, towards the end of the last ice age. A later maker, L1229, appeared around 5,500 years ago. Most of the descendants of the founder of this marker seem to have moved south toward the Iberian Peninsular.

The most downstream marker so far discovered that Kai has is L812 which was discovered in late 2011. It appears to date from around 4,500 years ago. So far ten people have tested positive to this marker and their distribution suggests that this marker probably originated from a man living in or near the area of Portugal. A number of these, including Kai, trace their most recent ancestry back to the Briitish Isles. The British component of L812 probably migrated from Portugal to the British Isles through trade which moved along the Atlantic Coast of Europe stretching back before the Roman Empire.

More information:

Kai's Y-STR data

National Geographic's Genographic Project

Family Tree DNA

DNA Heritage

Below: is the phylogenetic tree of branches after the M223 marker compiled by Ken Nordvedt..