Hello~That is an interesting question. I did a search on this and this was my favorite definition. I hope it helps:
An accent may be identified with the locality in which its speakers reside (a regional or geographical accent), the socioeconomic status of its speakers, their ethnicity (an ethnolect), their caste or social class (a social accent), or influence from their first language (a foreign accent).
In other words, I think it is a person or group that you are around the most, a person naturally will pick up their accent. I was born in California, but lived in the South many years, to this day, folks still say I have a type of southern accent, I don't notice it, but they do.