In a Y-DNA test, a specific number of Y-chromosome markers are measured. In a pioneering study of the Sykes surname, in 1999, values for just 4 markers were measured. In an initial study of the Plant surname, beginning in 2001, 10 markers were measured. More recently, values for 12, 25, 37 or more markers are typically measured. In the Sykes study, 44% of the men tested with this surname matched one another on the basis of comparing the 4 markers that were measured.
In general, the larger the number of Y-DNA markers that are measured and found to match, the higher the chances that the matching individuals are male-line related. However, if the tested individuals do not have the same surname, they may only be male-line related in the times before surnames began.
An interim case is that for a set of surnames, such as Cornwall, Warren, and Somerset, for which some of the individuals may have an intact male line of descent from the Plantagenets. Clearly here, we are not considering the entire world population and so the chances of finding a match are much reduced. However, it also needs to be considered how common is each signature in the general population and whether a match may have arisen just from random chance. This latter consideration is particularly important for the Warrens, since many of them have been found to have a Y-DNA signature that is identical to the so-called WAMH or Western Atlantic Modal Haplotype, which is the most common signature for the general population of men in Western Europe. For the Warrens, many of them have the WAMH right up to the 25-marker level.
The situation is rather better for the Plants. The most common Y-DNA signature for the surname Plant/Plantt is denoted PMH (Plant/Plantt Modal Haplotype) and this Y-DNA signature is a genetic difference of 7 from the WAMH at the 25-marker level. However, the PMH is only 1 mutation different from the WAMH at the 12-marker level (marker DYS439 has the value 11 for the PMH instead of 12 for the WAMH). As a result, there are several close matches between the PMH and Warren signatures at the 12-marker level. However, great care has to be taken not to read too much into these close matches between Plant/Plantt and a Warren at the 12-marker level.
Currently (at August 2007), Y-DNA results are available for 68 Warrens and 9 Warings of which 2 (1 Warren and 1 Waring) match the PMH exactly at the 12-marker level. This is only 2.7% of the total of Warrens/Warings tested however; and, at the 12-marker level, 2.5% of Western European men have the WAMH and around 0.9% have the PMH which is just 1 mutation different. Thus, it is not a particularly significant result to find that 2.7% of those surnamed Warren/Waring match the PMH at the 12-marker level. If Warren/Waring matches to the PMH were found to hold up at the 25-marker level, that would be a far more significant finding.
Return to: Plant Y-DNA testing Project Page