@Background Pony #19CE  
Because the situation is complicated. Like shown with the CMC, unlike Twilight in Twilight’s flashback, young ponies already have their talent prior.
 
But Twilight is the Element of Magic, the non morality based element. Does that mean that her magical power is not tied to her BORN talent? Is the pre-existing element of magic powering her, or is she powering it? As far as we’ve seen the show suggests the former. She has lost control of her magic more then any other unicorn.
 
But that’s not to put down Twilight. A near endless supply of magic or not, I honestly don’t think she would of been able to lift up the Ursa Minor had it not been for her friends being in danger. I think there’s a limit to what she can control, but her will expands that. In contrast, when she looses it completely, she’ll transform everything, turn into a rapidash (hurting herself), or accidentally blow up her roof top.
 
In other words, Twilight’s body is like a giant battery of magic, but she can only access so much. Even now, she can barely control a tiny bit of the power she unleashed as a child.
 
So to answer your question, we have established stuff, and unestablished stuff, like the full explanation behind the Element of Magic. This is the uncertainty, and how I am unsure.
 
Also, if anyone can tell me how RD as an adult is 10x weaker then she was when decided to go her fastest as a child, please let me know as well. RD’s sonic rainboom is almost the size of a football field, but the very first one by a child was more then a mile wide…yet it took a decade to retrain?!
 
One theory helps explain Twilight magical power as well, and the second theory is too scary to imagine. Both could be true at the same time, but we don’t have enough evidence for either. Again, unsure.
 
Its only going into S4, its not like their ready to give enough evidence on everything.

@CronoM  
You answer “Not sure.” but you also say “Magical power she was born without. This is all established stuff.” How can you say it’s “established stuff” if you’re unsure about it?

@Background Pony #19CE  
Not sure. (shrug) They left it completely in the air, as Celestia never talks about the Sonic Rainboom. Once she does, we’ll know yes or no. They’ve already established most ponies have their talent even before they have their cutie mark, but Twilight didn’t.
 
Since its not a power she can fully control, we have to assume its a by-product of being the Element of Magic, not the other way around. Like the Avatar State in Avatar the last airbender.
 
Twilight Sparkle had a natural talent for star gazing and magical knowledge. Magical power she was born without. This is all established stuff. I don’t know what to make of it, but without the first Sonic Rainboom, none of them would of become Elements of Harmony.

@Background Pony #19CE  
I always guess it just shocked it out of her.

@CronoM  
So, you really believe that Rainbow Dash’s Sonic Rainboom gave Twilight all her magical power?

@Princess♠Molestia  
@DoomPony  
You know as well as I do that Twilight didn’t HAVE that. Its known continuity from ep 23. Unlike CMC and their inate skills, Twilight herself didn’t have any strong magic potential until the Sonic Rainboom.

Do we have a name for her yet?

First half of that statment is nice if she was trying to each her daughter to use her own magic.
 
The second half of the statment makes mommy sound like an asshole and is just confusing.

You totally can. It’s magic, duh.
 
Also: ewww, spurts.

@Princess♠Molestia  
It required several home repairs a week, which is slightly more than average.

Only can only imagine how Twilight’s must have been.