How do you explain your spell "lore-wised" ?

The title is a bit confusing but basically...

Let's say I want to play a draconic sorcerer, with a white dragon has an ancestor, and his backstory is that he froze his village by accident, so a ice/cold flavored character.

But let's say I also want to use strong spells like fireball, how do I justify its existence ? Its easy for a wizard, bc I can just say that I learned it (bc im smart yk), but what can I say for a sorcerer.

"My family was frozen bc of me, I cant control that ice in me.... but i can also use wall of flame bc its strong".

For me that doesnt make any sense, at least in RP

Do y'all have something for that ?