"...with the men being killed or driven off and the women being seized as wives. The DNA of the modern population shows strong Norwegian origins in male DNA but Pictish traces in that of the women."

I'm sorry, that doesn't make sense to me. The original captives may have been Pict women, but that should not mean that descendants of these would be Pict(ish) in DNA if women but Norwegian(ish) in DNA if men. The second does not follow from the first, unless there is something in biogenenetics that I don't understand, which is perfectly likely.