I think it would be a very interesting twist if Obi-Wan fathered a child at some point in time, perhaps while on Tatooine, and he showed up in Luke's Order. Son or daughter doesn't matter I guess, but I think it would be interesting if he challenged Luke for control of the Order. Of course this would never happen, but it would be so incredibly epic. Skywalker vs. Kenobi Version 2.0!!