Dan Savage points us to Mormon’s Secret:
The ancestors of Team Mahonri Moriancumer designed and fabricated the very first Mormon temple garments in 1842. Each of us are related to one or more of the original members of the Quorum of the Twelve Seamsters, a secretive but important group in early Mormon history. Our genealogy clearly shows that by May of 2012, our families will have been directing the creation and production of magical Mormon underwear for 170 years. You could say this particular Mormon secret is a family secret.