Law of Hybridization

All of the five races currently known to live within Hybridis are capable of interbreeding, hence why're the five races and not the five species (according to most definitions of species). It is usually difficult to identify a hybrid at a glance and in most cases is of little significance. As a general rule cultural distinctions tend to matter more than racial ones for the people of Hybridis. A mixed culture heritage is far more likely to be stigmatized and looked upon with suspicion than a hybrid.
Suppose there are children of a human father and orc mother. Instead of looking like a cross between the two races their children would look like one or the other, most would be indistinguishable from a 'full blooded' orc or a 'full blooded' human. Although the exact percentages for which parent the child takes after is unknown, it is heavily slanted towards the mother.
However hybrids do inherit some traits from their other parent, though with the exception of highly unusual cases those traits aren't something visible. Typically they're minor things like a human with a lizal parent being able to comfortably stand still for longer than most humans would. There are only commonly inherited traits, not every human with a lizal parent will inherit the same lizal traits.
Dragons however follow their own set of rules when mating with the five dominant races because of their shapeshifting. The child of a dragon and one of the five dominant races will always be of the non-dragon race (regardless of what shape their dragon parent was in during conception) but with tails and wings, along with immortality and the elemental control of their dragon parent. In very rare cases the tails and wings may not manifest until a later age.
On a final note due to hybrids not being their own race there is a naming convention to designate what they are hybrids between. Returning to the earlier example of an orc and human couple the human children would be referred to as orc-born humans while the orc children would be referred to as human-born orcs. Children of dragons are always referred to as dragon-born [whatever race the other parent is].

Type

Natural