Board Thread:Theories and Speculation/@comment-30415965-20171104121848/@comment-734582-20171105112013

BlazeRelease wrote: I think, he's asking about why all the Konoha ninjas of the past generation had kids at the same time. It's often the case that people among a friend group get kids at roughly the same time.

It's also important to note that Naruto only follows a handful of people in a world of hundreds of thousands of ninja. So it's also the mother of all sample biases.