Between 2000 and 2010, the population of Park Slope increased by 2 percent. But the population of residents under the age of 18 fell by 5 percent, according to an analysis of new census data by Fucked in Park Slope. The neighborhood, of course, is famous, nay, notorious for its unique type of parents and its copious strollers, not to mention the baby bumps visible up and down Seventh Avenue. So how can this be? Is it that graduating teens outpaced the number of new births? Or that even Park Slope got seriously undercounted?