"DNA test can detect Picts' descendants"  reports The Daily Telegraph, today.  So far, so good.

 “A geneticist has created a DNA test for “Scottishness” that will tell people whether they are direct descendants of the Picts.”

Uh-oh.  I think the journalist added that middle bit about “Scottishness” himself.  It is not wrong in the widest sense, but it is not accurate either.  You see, the Picti were the real McCoy, a real native tribe like the Iceni and not the Johnny-come-lately, immigrant, warrior Scots and English who were Irish and German, respectively.[1]  The Scots were in fact invaders from Ireland and were distinct from the Picts and Gaels much as the Anglo-Saxons were distinct from the Celtic, British  tribes they displaced.  You will note that Dr Jim Wilson, of Edinburgh University, does not actually say that his DNA tests can determine “Scottishness”. The test is for “Pictishness” not “Scottishness”.

By the 11^th Century AD “Scot” appears to have become a description for everyone living in that area now known as Scotland, in the same way that "English" came to mean more than just Angle and/or Saxon. However, a descendant of the Picts can claim to have lived in these islands since time immemorial, whilst true Scots, like the English, a mere fifteen centuries.[2]

[1] Wikipedia reckons that the Picti and Gaels became the Scots, which is correct, but the Scots were a distinct tribe who hailed from Ireland and who colonised a significant part of what became Scotland.  Strictly speaking, therefore “Scots” are Scots, Gaels and Picts but the Scots were the politically dominant ethnic group who forged a nation in their image, in much the same way as did the English, south of the border.

[2] Examples of other jarring historical inexactitudes guaranteed to cause a fistfight if blurted in the presence of any descendant of  Hengest and Horsa during the course of an otherwise civilised conversation:

“When the English painted themselves from head to toe in woad, lived in mud huts and rode around in chariots, the civilised Romans lived in centrally heated villas.”

“Hadrian's Wall was built by the Romans to protect the English from the Scots.”

“The Legions of Emperor Claudius conquered England in 43 AD.”