Some mages are inborn to specific Talents or abilities. They require no training to use their particular specialization, however they still require enough magical training to be capable of tapping into their magic at all for it to awaken. As such, inborn mages tend to be identified and chosen to learn magic by mages looking for apprentices.
Around 5% of people are inborn mages. One can walk down a city street and identify several inborn mages, although they might not all have the same potential power level. 2% of all inborn mages are dual-inborn, with two distinct Talents. Only someone with a dual inborn who has Catalysm as one of their inborn Talents is actually capable of using magic from a young age spontaneously and with no education whatsoever. These are rare, often considered legendary or blessed by the gods.
Inborn magic is instinctive and comes as easily to the mage as breathing. Inborn mages tend to be more powerful with the Talent they are inborn to than mages who were simply trained, but trained mages will generally wind up being more skilled and capable of using a Talent with greater control and precision. However, inborn mages can also be trained or practice on their own in order to gain the same skill if they're willing to work at it.
One peculiarity about inborn magic is that a mage's ability may not be one typically seen outside of non-inborn magic. It may be hyperspecialized, work strangely, or simply be something that has never been seen as a spell before. This is often how new magic is discovered.
Inborn mages tend to be those who spent a good deal of time in their previous life learning and studying magic. As such, a soul can lose or change their inborn Talent upon rebirth if they squander their potential or learn something else.