Well, it is debatable whether there ever existed Germanic (and Celtic and Scandinavian) cultures with no contact with the mediterranean ;-) It is not very far off, and there is evidence for trade between the baltic and the mediterranean at least as early as the neolithic.
But there's no doubt that all forms of runes used in Europe were related to (and descended from) Phoenician (probably by way of early Greek) alphabets. This is especially evident if you look at early italian runes.
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