Just to clarify, these people are not part of the modern LDS. They are a radical splinter group and a closely insulated cult lead by Warren Jeffs that believes that its Gods will to force 14 or 15 year old girls into incestuous marriages with their uncles or first cousins (or even worse).
Yes, Warren Jeffs is a wack-job pervert, as was his father before him, but he's not a Baptist. Do you think that there might be something in the teachings or in the tradition (or in both) of Mormonism that lends some support to such an abusive way of life?
The life of Joe Smith their prophet.