Marc,
that's a good question. As I explain in the section about Sources of the Biblical Tree Project: http://www.geni.com/projects/Biblical-Tree this is a very difficult issue to deal with. There are literally hundreds of sources, canonical and not, for this period and the traditions involved. So unless I have a specific primary source that says something specific is NOT as listed in the secondary sources, then I tend to not rule it out.
I consider my main primary sources to be the KJV, Quran and the Jewish Bible. I know that it is [Catholic] tradition that Jesus didn't marry, but is this actually sourced? Are these traditions sourced in anything as near in time as other writings, such as those of the Gnostics? If not, we'd have to consider those Gnostic writings also primary sources.
I don't really think that "a preponderance of evidence" is really relevant for periods of time so far removed from the present. Especially so, due to extensive censoring and efforts to destroy all sources that did not match religious dogma of the time(s). It is obvious that even regardless of that, the "official version" would be much more prevalent. As I also said, the historical cultural likelihood of Jesus being single at his age, was about zero. The Catholic "disapproval" of carnal marriage, came at a MUCH later point in time, and many Christians would like to claim that Jesus was the perfect.... Jew.
Some years ago, I had extensive correspondence with a present-day Gnostic, who gave me references to such sources. So I have actually seen them, but not being even remotely Christian, it's a non-issue for me (so I can't recall the exact sources). I'm just doing my job to ensure that all reasonably-valid opinions that are added by people are expressed in the tree. That is also why the profile for Jesus will remain locked: Too many nutcases wanting to impose their theology on other people's genealogy.
Shmuel-Aharon Kam,
Geni Curator