Paternal ancestry can be traced by DNA on the Y-Chromosome (yDNA for short). Under normal circumstances, only men have a Y-chromosome, which they inherit from their fathers and pass on to their sons. However, women can also find out about their paternal ancestry from the yDNA of a male relative, for instance their father or brother. The yDNA traces a man’s unbroken patrilineal line back way into the past in the same manner that maternal ancestry is traced by mtDNA . Recent research has revealed that some women also carry a Y-chromosome, albeit in very low amounts. This can be due to a small proportion of body cells deriving from a separate foetus, perhaps an unborn twin. Our Y-Clan test will detect these Y-chromosomes over a certain threshold. In these rare cases a woman's paternal ancestry may be established.The presence of a Y-chromosome in a woman usually has no effect although in some rare cases it has been implicated in gender identity. Scientific research throughout the world has shown that all our paternal lines are connected somewhere in the past and that these connections can be traced through yDNA. As with maternal genealogies defined by mtDNA, men tend to cluster into a small number of groups, eighteen in total, which are defined by the genetic fingerprints of their yDNA. In native Europeans, for example, there are five such groups, among Native Americans there are four, among Japanese and other East Asian people there are five, and so on. The men within each of these groups are all ultimately descended from just one man, their clan father. These ancestral clan fathers were not the only men around at the time, but they were the only ones to have direct male descendants living today. Other men, or their descendants, had either no surviving sons or only daughters. These clan fathers in turn had male ancestral lines that ultimately converge on the common paternal ancestor of every man alive today. This man, known as “Y-Chromosome Adam”, lived in Africa 60,000 – 80,000 years ago. For our classic Y-Clan service, we read twenty-six elements of your yDNA fingerprint and build up a signature. By comparing it to thousands of others from around the world, we are able to deduce your paternal clan and your ancient ancestral father. Not only will we be able to tell you from which ancient clan father you are descended, we will also give you some information as to when and where he lived. The genetic elements of your signature also change over the generations and by comparing your genetic signature with those of others it is possible to tell, on the balance of probability, how closely you are related. In many countries, surnames are also passed down from father to son, just like the Y-Chromosome. This means that you may also use your Y-Clan results to investigate your paternal lines alongside more traditional genealogical sources in a very powerful combination. For example, you will be able to compare your Y-Clan results with those of other men with the same surname to see whether you share a genetic connection.