Originally Posted by Starlights
If you are a rogue, perhaps you started developing your abilities around 7-8-9 years old throughout your teenagers years, stealing food at the marketplace smile. You might also have followed or force to follow a street gang. Knives are easy to hide and carry while you are running away.

If you are a fighter, perhaps you have followed a role model during your teenagers time and practice with the sword (GoT Aria practicing with the sword her brother gave her). Although I would see Aria as rogue/fighter. What you think ?

-S

That is not at all in line with Dungeons and Dragons. Now, 5e did reduce Rogues to just petty thieves as seen in the difference between the editions:

Originally Posted by 3.5e Player's Handbook
Rogues share little in common with each other. Some are stealthy
thieves. Others are silver-tongued tricksters. Still others are scouts,
infiltrators, spies, diplomats, or thugs. What they share is versatility,
adaptability, and resourcefulness. In general, rogues are skilled at
getting what others don’t want them to get: entrance into a locked
treasure vault, safe passage past a deadly trap, secret battle plans, a
guard’s trust, or some random person’s pocket money.

Originally Posted by 5e Player's Handbook
Every town and city has its share o f rogues. Most o f
them live up to the worst stereotypes o f the class,
making a living as burglars, assassins, cutpurses, and
con artists. Often, these scoundrels are organized
into thieves’ guilds or crime families. Plenty o f rogues
operate independently, but even they sometimes
recruit apprentices to help them in their scams
and heists. A few rogues make an honest living as
locksmiths, investigators, or exterminators, which can
be a dangerous job in a world where dire rats—and
wererats—haunt the sewers.

However, it still doesn't follow that they are commonly orphan children who are making their living as petty thieves before they even hit puberty. Most would be starting in adulthood just the same.

Though, this does give rise to the fact that Astarion as a rogue just doesn't work in 5e because 5e oversimplified things wildly - though he would be an ideal rogue in 3.5e.