successions

catenae (or catenas), catenations, chains, concatenations, consecutions, nexuses (or nexus), progressions, sequences, series, strings, trains

files, lines, queues, ranges, rows

echelons, ranks, rows, tiers

chain reactions

belts, circles, cycles, vicious circles (also vicious cycles)

continua (also continuums), gamuts, gauntlets (also gantlets), scales, spectra (or spectrums)

flows, rivers, streams

heredities

ancestries, births, blood, bloodlines, breedings, descents, extractions, family trees, genealogies, lines, lineages, origins, parentages, pedigrees, stocks, strains

families, houses

kins, kindreds, relations, relatives

races