“Surely we have learned by now, from the experience over centuries, that the basic family provides the most stable and secure foundation for society and is fundamental to the preparation of young people for their future responsibilities,” said Elder L. Tom Perry of the Quorum of Twelve.

“We should have learned by now that alternate styles of family formations have not worked and never will work,” he said.

Along the same lines,

“Marriage is meant to be and must be a loving, binding, harmonious relationship between a man and a woman,” church elder W. Douglas Shumway told about 21,000 members of the Church of Jesus Christ of Latter-day Saints gathered for the 174th General Conference.

sources: http://www.harktheherald.com/modules.php?op=modload&name=News&file=article&sid=18310&mode=thread&order=0&thold=0
http://deseretnews.com/dn/view/0,1249,595053824,00.html