Do you have British Accent?

Everywhere I go, people say that I have a British Accent. This should not be surprising because back in China the official accent taught at school was British accents. Even though I have adopted as much American accent since I came to the states, most notebly the "er" sound, the Americans can still detect my British accent and ask if I learned English in UK or Australia. I told them that it is what I learned in China at school, but they do not buy it. And I see why: most Chinese from China do not have the accent that was taught in school.

Now my question is: do you have a british accent if you first learned Engilish from China? If you do not, why???