- The Observer,
- Sunday February 9 2003
Scientists use two main sources of genetic data to unravel the secrets of a person's ancestry: the Y chromosome and mitochondrial DNA.
The Y chromosome is one of the bundles of DNA - 'the golden molecule' from which genes are made and the structure of which was uncovered 50 years ago this month by Francis Crick and James Watson - that lie inside the nuclei of our cells and which determine our physiological characteristics. The Y's function is simple: it confers masculinity on the developing embryo.
However, unlike other chromosomes - which are made up of random sections of our parents' chromosomes - the Y is inherited in its entirety from an individual's father. He in turn inherited it from his father. The Y chromosome therefore gives researchers a means to probe an individual's male lineage.
By contrast, mitochondrial DNA is inherited only through the maternal line. This form of genetic material is found outside a cell's nucleus, in the mitochondrial organelles that manufacture the chemicals that provide our cells with their energy.
A man does not pass his mitochondrial DNA on to his offspring. Mitochondrial DNA therefore follows an unwavering path through the maternal lineage.
