Sorcerers have innate magic, and in the case of this setting, that most of the time is due to some godly shenanigan or its consequences. Of course, if they were immediate descendant of a god, they would be a god or demigod themselves, which is not the case for any of yall.

What is usually the case for sorcerers would be either some close-yet-distant descendant of a god, or a god blessed them/their family line. (or some godly event happened and you happened to be there) There is often the case of certain influencial sorcerer families being proud of some 'origin myth' of some sort, which whether or not happened as they say it did, who knows.

There are countless possibilities for origin myths for someone's sorcery, like, X god was mourning and their tears fell on my mom when she was pregnant, or X gods hair fell into my soup when i was a baby, get creative!