UPDATE: Per a recent DNA test on a man who shows his lineage back to Reverend Andrew Baker Davidson....who was a son of William Davidson and Martha Baker....that family is the same overall Davidson family as the other William Davidson from PA who married Sarah McCoy and the widow Mrs. Elizabeth (Wilson) McCrea (and this was quite a surprise). Donors from both of those two Davidson lines have "matching DNA," and they are in "Family 16" at www.davidsongenes.org
. It had previously appeared that the William Davidson who married Martha Baker was almost certainly a member of DNA "Family 10," but the new DNA result mentioned above does not support that.
The John Davidson who married Mary Thompson (lived from 1757 until 1835; he was a son of the John Davidson who died about 1762 and who had married Elizabeth Maben or Houston) was a member of the unrelated DNA "Family 12" (per yet another DNA test).
Finally, the family of the John Davison, Senior (died about 1802) who married Mary Allison (and their son John Davison, Junior (died about 1798) who married Sarah "Sally" Rootes) has no DNA donor at this time. Two members of this last Davison family married into the Davidson family of William and Martha (Baker) Davidson, but we do not know if those two Davison/Davidson families were "blood related" to one another.