The World of Mythis: Magicians

In the world of Mythis, there are three known ways for one to become a magician.
The first is to be a magician born. To be filled with magic from the time of birth, and have it grow with you through the passing of time.
A magician born is must be patient, for their magic does not grow stronger through constant practice, but only with time. Therefore, a magician born is most powerful in their later years, and at their must vulnerable in their youth.
The second is to be a magician borrowed. These magicians are given their magic by one of the magician born, through a sharing of magic that binds the two together. Unlike a magician born, a magician borrowed does not increase in power as the age. Instead, they maintain the same amount of magic that was given to them by the magician born.
But when the magician who gave them their magic dies, a magician borrowed loses their magic.
The third is the magician found. Unlike the magicians who are born or borrowed, a magician found receives their magic from ancient artifacts that have been imbued with magic.
So long as they possess the imbued object, these magicians have access to whatever magical abilities the object provides.
Though they are limited in ability, a magician found is the only kind which can reliably pass on their magic to others without the magic fading upon their death.
These three are the only known ways for humans to perform magic in Mythis; though there are rumors of one other way.
Of magicians stolen, who somehow drain other magicians of their magic in order to increase their own abilities.
Is there such a thing as a magician stolen?
Hopefully the world of Mythis will never find fact in such a tale.