This is just a simple counterexample, but I'm pretty sure Jack Kornfield has children or at least a child. Also, he definitely had them after he was enlightened, because he used to be a monk. I'm sure if you look at the senior teacher lists of most dharma centers you will likely find many with children. I'm not quite far enough on the path to comment from experience, but I would guess the likely mild-moderate correlation might have more to do with the commitment to retreats/meditation/getting enlightened + western career obligations/schooling taking away the required time needed to be there for one's children. Other theories could have to do with minimizing suffering by not creating, etc, etc...but I'm not qualified enough to evaluate the second theory, so I'll let someone else explain their views on that which are likely just "views" which someone else could easily refute to create an endless argument.