I have never hearda anything else than our sheep being from Norway (or Scandinavia in general).
If she finds DNA that says they are from Gotland there could be a simple reason for it. Since sheep were taken from Scandinavia to Iceland about 1200 years have come and gone, during wich time a lot of influx of new sheep DNA to Scandinavia has probably happened. But in islands like here in Iceland, in Shetland islands (Hjaltland like we call them), Faoerer island and Gotland the old stock was preserved and isolated.
Probably because the sicknesses that must have come with the migration of sheep to the rest of Scandinavia, and we people of the islands have not wanted to endanger our sheep when they have heard about the sicknesses.
About weather sheep from scandinavia have been part of the genetic makeup of the british sheep, it is probable, as England used to be called Danish Law, as it was under Danish control for quite some time.
Sometimes people seem to be able to spin crazy stories from little or no evidence, probably they already had spun them, but then tried to find any proofs for them. It is not scientific.
Yup. That was my people...they were R1b (DYS390-23) from Denmark. If You're Irish, you're probably R1b (DYS390-24). I learned that this past year when I had my family DNA analysed. BTY, my last name is LAMB (hence, blam).