SB, you're absolutely right that there's no way to tell from someone's Masters times what kind of parent they are. That's ridiculous.
However, I think it is fair to say that for any Master to run 100mpw and perform at a relatively high level he or she has to make running a very high priority in their lives. No 45 year old man is going to rip off a 14:30 5K with an approach to training that involves nothing more than "I get a run/workout in when I can fit it into my day." No, I'd say those folks have a job and lifestyle that allows them to maintain a very regimented training program. That means they have to work extra hard to balance the other aspects of their lives (profession and family), which can be done but not without some inevitable conflicts and some tension. It just can't possibly be any other way. There is a big difference between a grown family keeping fit and a grown family man running 100mpw and traveling to meets.
The comparison to writing fiction is a bad one. No matter how fast someone is as a Master, it is still nothing more than a hobby. Writing fiction really well is a vocation. And, most accomplished writers' personal lives are complete train wrecks. Hemingway was on his 4th wife by the time he won the Nobel Prize. Not a good example for domestic harmony.