They are persons .... each hogar [household] has one member who is an ejidatario ... generally, this means each family unit living together - of course many households will be related to others, as sons grow up and build their own houses, also there is intermarriage to a degree [but not that much, as there are strong social mores against inbreeding] .... over time, everyone in an ejido is related to everyone else, in some manner
But each home has one member who is a miembro of the asemblea ... traditionally always the alpha male if there was one, but increasingly the wives are showing up as ejidatarias in some places now, which sets up interesting dynamics among the old priísta types, lol ..... never get sucked in by that macho mejicano myth - the ruler of the home is the mother
So in Mulatos there are seventy-eight ejidatarios, that means there is a total population of souls of perhaps five hundreds ... that is using a multiplier of six, roughly .... just a guess ...... in our ejido, which has roughly four times the number of ejidatarios [and several ejidatarias, one of whom is my wife - a source of great fun to us], a multiplier of six works pretty well [though it is hard to make an accurate population count, as so many go away to work, or study, then come back for long periods ... often difficult to say where exactly they 'live', but they remain part of the village in any case]
The family is the basis of all structure in mexicana society ... this is more true there than in any other place, maybe ... so from that, combined with the land reform efforts, and reaction against control by the church, stem the ejidal system