Cornwall has been a relatively isolated part of the British isles. Up to 1550 it spoke its own language, and had its own form of government and currency until the 1700s. Compared with other parts of Britain there has been little intermingling. Except perhaps from Devon, and limited influx from Ireland and the continent, there has been limited in-migration until the present century. After 1850 however, when the great mines began to play out, there was a major exodus to other parts of the world where mines were to be found (Australasia, North and South America and South Africa).
Cornwall had the largest known tin deposits in the world for thousands of years, and initially a great deal of alluvial gold. The first metalworkers to arrive in Britain were the Beaker People around 2500 BC, and they worked Cornish gold and tin extensively, while constructing a large number of ritual sites and burial chambers. A significant part of Cornwall's ancient DNA stems from this very early period: there are many pockets of what appear to be early Bronze Y-DNA in Cornwall, along with later Continental and Irish intrusions.
Project membership is free and open (on a trial basis) for anyone with a Y and/or autosomal test. It is expected that members will have a known Cornish ancestor.
There is a separate Cornish mt project for people who have a Cornish female-line ancestor and have tested mitochondrial DNA
AUTOSOMAL MATCHING AND "Cornishness"
For autosomal, one should be 1/16 Cornish or better, as otherwise there may be no matches. Internal matches can be found by using the Advanced Matches facility on Family Finder Anyone who is 1/4 Cornish or more can expect to have at least four matches (though siblings may be more or less Cornish).
People who transfer the new Ancestry or 123andme autosomal files will not have 'speculative matches' and so have many fewer matches.
Other possibilities are to take the LivingDNA test, which works well on the distinctive Cornish DNA. There are a few admixture tests on GEDMATCH that also test this.
CORNWALL ADVANCED YDNA PROJECT
Our associated research project that has found a great deal of rare and unusual DNA in Cornwall, dating back to Beaker settlement during the early Bronze Age in many instances. Because of its long isolation, it has been a 'museum' for unusual Y-DNA.
Men in this project with a Y-37 test or better can join the CORNWALL ADVANCED YDNA project as well if they have a clear paper paternal line back to Cornwall, and if they have taken a SNP test (usually a pack, or Big Y). In some cases we will relax these two conditions - please contact the administrator for options if you are interested in assisting with the research.
You are particularly encouraged to improve your Y-testing if you have very few Y-DNA matches, which is the case for many Cornish men.