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CORNWALL ADVANCED YDNA

Sub-project of CORNWALL
  • 184 members

FAQ

What is unusual Y-DNA? Why does Cornwall have so much?

Unusual may mean either a rare haplogroup (defined by a SNP) or who have very few SNP matches. We have a lot because there was very little movement into and out of Cornwall for many centuries, consequently over time many men's Y-DNA became widely separated from the DNA of men in other parts of Britain.

What is a 'pocket'?


This is a haplogroup that is largely restricted to or heavily concentrated in Cornwall and maybe a couple of other places. It has probably grown or expanded in Cornwall from a single man over millennia.

- Cornwall has one clear pocket from the Iron Age, R1b-U152>>CTS11151. The line came from the continent about 900BC and eventiually became established in Cornwall.
- The early pocket R1b-DF27>L617>FGC14951 dates back to the mid-Bronze in about 1800BC. It is found in high concentration in Cornwall, where it probably came to Britain through the Iberian tin trail
-  The P312>L238>>A9434 line. Despite dating back prior to 2500BC, L238 has been found only in the Isles. This A9434 pocket has three men in the project, and is also found among ARMSTRONG of Northern Ireland.  
- The Drake R1a line, severa branches of R1a>>L664>S2894>YP285>YP282; found in SW England.

There are also a number of old 'singletons' - 

What is the Y chromosome?

Only men have the Y chromosome which is passed almost unchanged from father to son. It is the smallest chromosome with about 57 million bases and only contains 344 active genes, most of which are believed to relate to reproduction and sex determination. It is full of 'rubbish DNA' including a lot of recurring sequences and even a partial copy of of an old X chromosome that has been randomly bound in. 

It contains several large 'palindromic sections' with two branches that are almost mirror images. Some STRs take counts on either arm of the palindrome and are therefore 'double-valued' . Sometimes when one arm is found to be faulty during copying, it will be overwritten with the copy of the other arm to clean it up - which will make both values of any STRs the same.    



What is a false match? 


These are Y-matches of people with different surnames which occurred either 

a) before surnames were invented. These can often be eliminated with a 111 marker test.

b) where the DNA of descendants of unrelated men spreads out and crosses over each other. This is very common with small numbers of markers (12 or 25). These 'false matches' can usually be eliminated with SNPs or by going to more markers.


Can DNA be used to break down brickwalls or find ancestors fro adoptees?

We have quite a number of success stories. Mostly these are because we were able to identify which branch of a family someone came from, which enabled us to target our paper search. However it is sometimes possible using 111 markers or SNPs to work out which of two matching cousins a man is more closely related to.