assume everybody has children and they continue their profession

That was kinda-sorta true for peasants in the XIII century, it is very very far away from true now. And if you're talking about being unable to hire people, this is just plain silly, small plots of land cultivated mostly as a hobby (it's very hard to support yourself at a reasonable standard of living from a plot of land that only you and your immediate family can work) are economically meaningless in a normal economy (as opposed to e.g. Soviet Russia).