I don't know how they do it. I didn't. When I had two young kids, my whole life revolved around them. If I couldn't take the kids with me, I didn't do it. I couldn't ride with two kids, but I could downhill ski with them (first on my back, then between my legs and then on their own), I could hike with them, gardening, household chores, bicycling... I didn't ride, I didn't go out. I never had a babysitter until finances got wonky and I had to work. If I wasn't at work, I was with the kids.
Now they are bigger, but life still keeps me busy. I ride when I can. Sometimes I don't get out for a couple of weeks, sometimes 3 times a week. Rarely more than that and during my busy season, I will miss 4 weeks of riding altogether because usually the only time I have is on the weekends. This time of year, my weekends are spent working or skiing because the rest of the family skis, but they don't ride. So, ya, family comes first.