They don't disown their roots--they change them and then deny they ever existed. The Book of Mormon has been changed numerous times (someone counted over 2000 changes). Copies of the original are exceedingly rare since they have been called in and destroyed. There is one in the Bancroft Library at UC, Berkeley. There is also an original Book of Commandments there as well as copies of the early Times and Seasons which contained many "Thus sayeth the Lord" commandments. (My information on this is 30 years old so may have changed).
Your comment has given me an idea.
As a lawyer, I am great believer that the facts often shout so loudly that the argument can't be heard. Has anyone ever taken the 'original' text of the BOM and simply done a redline/strikeout against the 'current' and published it.
Because there are no 'original documents'/translation issues (as with the Bible), then a single change in the BOM is devastating to its credibility.
Is the text of that original at Bancroft available on the net?