Would using wood dowels to attach lumber to a tree for tree house be better for the health of the tree?

Next year when I move to Austin (TX), I want to build a tree house for my grandchildren, but I would like to avoid putting nails into the tree. What I plan to do it to drill holes and put in wood dowels in the trunk to act as supports. Would this do less damage to the tree than putting in metal nails, which rust and can be chemically broken down by the tree's disease defense system?