@Background Pony #D07C
 
Brown Sugar was about the same age, five, when Sweetie Belle turned five. When the events seen in “Canterlot Boutique” happened, Sweetie Belle was about ten years old. Which means Brown Sugar was ten years old there, too. And that pony on the left, it’s not how a ten year old filly looks like. It’s clearly an adult mare.
 
And Brown Sugar was seen in the present as well, in the same age. Which could just be time travel or have another reason, but either way, it’s clear these are two different ponies.

@Background Pony #D07C  
Not really far apart enough to be honest…

Or they’re the same person, since one of them’s from a flashback.

@Beau Skunky
 
That already happened. Since Season 4, the show really took that up a notch, with featuring ponies who look different than most ponies we’ve seen in the show. 
That’s another reason why it’s worthwhile to keep an eye on the background and to pay attention to background ponies. 
Background ponies are those who really fill the show with life and who demonstrate that there is not just a bunch of manecast ponies, but a whole world filled with inhabitants of all personalities, sizes and shapes. 
One just has to look closely and can then see so many stories being told that happen behind the main plot of an episode.

@CMC Scootaloo 
Agreed, plus I’d like to see more chubby ponies, or more variety in the body designs of ponies. I like how the recently introduced Plaid Stripes & Inky Rose were portrayed kinda lanky.

What’s interesting is that her mother (if we assume she is her mother, not related to her in another way) is rather corpulent, while Brown Sugar herself is rather skinny. 
Sure, she’s still a filly, but I think that goes to show nicely that preponderance isn’t genetic.

Same coat color, same eye color, same race even (despite that we know that this isn’t a requirement for relationship at all), same mane color and the same mane characteristic of having two colors in it….. A very clear case and she could either be her mother or her sister. Maybe aunt or cousin, but for those two, the difference in look would probably be bigger.
 
I’m glad I discovered this. That’s even more apparent than with Dinky and Derpy!

THERE GO MY HEADCANONS AGAIN

@Background Pony #FA4C  
Perhaps, though some got rather defensive of said fanon when one guy was making fun of it in a pic he drew. >>829427

@Beau Skunky  
Considering there’ve been two new images on Derpibooru in the past month showing them as being related, and they were both done at the request of the same person, I suspect that fanon is dying out.

@Minus  
Does that include the whole popular “Derpy & Dinky” thing?
 
Also, both ponies are kinda adorable.

@Minus  

 
@TexasUberAlles  

 
Double truth.

It’s 2015, man, why are people still doing this.

Every time I see a “they have the same colours so I bet they’re related!” post, I die inside a little more.
 
No, I don’t think they’re mother and daughter.