If you have any Mormons in your family tree, they have every right to
baptise your common ancestors. The problem arose when a couple of very
zealous Mormons were baptising people who were not related to them.
Those baptisms were undone by the Church.
Supposedly, a deceased person has the right to accept or reject the
baptism. I just imagine my deceased relatives saying "thanks, but no
thanks" and I leave it alone.