Hodgson DNA Analysis

Some commercially available DNA testing is based on Y-DNA or mitochondrial DNA. Humans have 23 pairs of chromosomes - a total of 46. Twenty-two of these pairs are similar, in both males and females. The 23rd pair, the sex chromosomes, differ between males and females. Here females have two copies of the X chromosome, while males have one X and one Y chromosome.

Hence a Y-DNA test on a male will be on only about 2 per cent his overall DNA. The Y-DNA is passed from father to son in every generation. It changes only occasionally, through slight mutations. Much of it is so-called 'junk DNA' and plays little or no part in forming our bodily or mental traits. It can tell us something important about our male-to-male ancestry and origins but it cannot tell us to what 'race' we belong, even if the concept of 'race' had a robust meaning.

Almost all of our DNA is a mixture taken from both our parents. About 98 per cent of male DNA and all of female DNA mingle randomly through the process of sexual reproduction.The realities of human intermingling and reproduction have made it impossible to identify pure or typical racial types.

Tests on mitochondrial DNA examine material inherited by men and women from their mothers. They can be useful to examine female-to-female ancestry and origins. But this too is only a small part of our DNA and it cannot be used to establish a 'race'.

As homo sapiens we are all descended from a relatively small group that moved out of Africa and spread north, west and east, roughly 80,000 years ago. Dispersal, natural selection in different environments, and other factors led to some genetic variations between relatively isolated populations. But genetic diversity within each of these populations was as important as diversity between them. Differences became even more blurred as peoples migrated and intermingled with others.

Recent studies of the human genome throughout the world have destroyed the old racial theories and classifications. It is widely reported that any two individuals selected at random from the world population will be more than 99 per similar in their DNA. Up to the middle of the twentieth century, and not simply in Nazi Germany, pseudo-scientific eugenicists and craniologists gathered empirical data on head shape, skin tone and hair colour in attempts to establish racial identities. Modern DNA research has exploded these racial myths.

Careful use of DNA analysis can help to direct our archival research and find our relatives. But beyond a few generations into the past, the records become scarce and then disappear. In any case, tracing our male-to-male ancestry back to (say) 1400 AD will involve about 24 generations. Literally millions of people living at that time would be our ancestors. The one male ancestor we might find (perhaps with our surname) would be one among several million others.