I had an acquaintance at work that is gay. We had extended chat sessions where I had to defend my views on marriage. I came to see the issue from a gay man's point of view. It affected me greatly.
At the time, I thought being gay was a choice. Probably the primary thing that turned this for me was a lecture by Emeritus professor William Bradshaw who visited Brigham Young University on Sept. 23, 2010 and delivered a lecture entitled "The Case For A Biological Origin of Homosexuality".
I was confused. All my life I had been told that gay was a choice. This lecture opened the possibility that it was not.
In December 2012 the church launched the website mormonsandgays.org
"Where the Church stands: The experience of same-sex attraction is a complex reality for many people. The attraction itself is not a sin, but acting on it is. Even though individuals do not choose to have such attractions, they do choose how to respond to them. With love and understanding, the Church reaches out to all God’s children, including our gay and lesbian brothers and sisters."
I have come to the same conclusion. I am not sure what causes homosexuality generally. From what I have heard it is not a choice.
I do believe strongly in traditional marriage. In the summer of 2014 discussingmarriage.org. I had heard of many of these secular arguments for traditional marriage. I think this site makes a good case the case for it.