Retsina is indeed made with Aleppo wine resin added during fermentation; thankfully it is filtered out during racking, so modern retsina is far less strong tasting than the historical wine -- which was historically credited with killing many non-Greeks who partook of too much Greek wine. To me it tastes like turpentine mixed with Pinesol. Of course the grape varieties used to make it are fairly poor tasting to begin with, so maybe retsina is the best use of those grapes.