What fruits are pomelos related to?
Pomelo
The pomelo, Citrus maxima or Citrus grandis, is the largest citrus fruit from the Rutaceae family. It is a natural (non-hybrid) citrus fruit, similar in appearance to a large grapefruit, native to South and Southeast Asia. The pomelo is one of the original citrus species from which the rest of cultivated citrus hybridized. The popular fruit is used in many Chinese festive celebrations throughout Southeast Asia.
Citrus taxonomy
Most commercial varieties are descended from one or more of the 'core species', citrons, mandarins, and pomelos, which share in common a complex floral anatomy that gives rise to more complex fruit. These core species, and to a lesser extent other citrus, have given rise to a wide variety of hybrids for which the naming is inconsistent. The same common names may be given to different species, citrus hybrids or mutations. For example, citrus with green fruit tend to be called 'limes' independent of their origin: Australian limes, Musk limes, Key limes, kaffir limes, Rangpur limes, sweet limes and wild limes are all genetically distinct. Fruit with similar ancestry may be quite different in name and traits (e.g. grapefruit, common oranges, and ponkans, all pomelo-mandarin hybrids). Many traditional citrus groups, such as true sweet oranges and lemons, seem to be bud sports, clonal families of cultivars that have arisen from distinct spontaneous mutations of a single hybrid ancestor.