Why does Sofia Vergara have an accent?

To quote Sofia Vergara herself:

"I go out to a mall or restaurant and when somebody hears me they'll go, 'Oh my God, it's your real accent'. I tell them, 'Yeah, I guess I'm not that good an actress!'"

Still, she admits, her comedic instincts may, at times, cause her to emphasize certain pronunciations

"I do make the accent a little stronger."

"I understand English; I read and write English perfectly, but the accent won't go away."

and:

"When I moved to L.A. and I wanted to act I did want to work on my accent... so I hired a speech coach. He was super-expensive."

"(I spent) hours and hours, because it's not like you can do it one time a week; you have to do it, like, five times a week, three hours a day... It was the money most thrown away (sic). I got worse. Look at me now."

(Note: Just like Gloria, the character she plays, Sofia Vergara was born and raised in Colombia)