In his book, Surprising Insights from the Unchurched, he mentions that they found that the unchurched who had at one time attended church (or who came from a family that attended church) were more likely to go to a church that was associated with the deniomnation they were previously affiliated with, or their family was affiliated with. I don’t have the page numbers, because the book is in my office now. Denomination was actually quite important to the unchurched people he surveyed.