A mating between a True Giant and another race will always produce a Half-Giant, although the child usually resembles the mother in size. If two Half-Giants mate, they will produce another Half-Giant, again almost certainly closely resembling the mother in racial features. If a Half-Giant mates with a Human, Elf, or other non-Giantkin, they will produce children resembling either one of their race, usually at about a half and half split.
Goliaths are the product of Giants, usually Ice, Hill, or Cloud Giants, and Humans, they are mostly found near mountains and are especially adapted to the cold. Firbolg are the offspring of Giants and Elves. The first Firbolg were most often parented by one Forest Giant, or sometimes a Hill Giant. However, as Forest Giants have almost all but disappeared of Ylembica, Firbolg are carried on through their existing numbers, or still sometimes by a Hill Giants and an Elf. Half-Orcs are the descendants of Orcs and Giants, usually a Stone, Hill, or even Fire Giants, boasting incredible strength, but often lacking in wit. By extension, Bugbears are just as much Half-Giants, as they are Goliaths that were corrupted by the touch of Myolg.