the answer is almost identical to a white jew, and the lebs were never expelled from the region, although one will note that, unlike almost everybody else in the region, they're also roughly half christian. i haven't seen a study, but it would be an obvious observation that the whiter lebs correlate with the christians, while the darker skinned lebs are mostly muslims.
there's a reason for this, and it's that the region was in fact mostly lighter skinned up until the arab migration c. 700. roman palestine and greek and iranian israel/judah were pretty white places. the lebs and jews are both the remnant of that ancient population, which was displaced by war and disease and partially replaced. these three subpopulations of white lebanese christians, white jews and white palestinians are the people that were actually there first, while the arabs moved in relatively late in history and brought a large number of african slaves with them, which darkened the skin of certain clans.
i'm just noticing this as i see pictures of lebanese politicians in the news. even the muslim ones basically look like italians, not arabs.