Accents, I love accents for some strange reason even if some of them annoy me like Boston - it just rubs me the wrong way -, deep Southern accents in the United States, and Cockney English - most overused and stereotypical accent to represent the British/English. Then there's Welsh, Manchurian, Caribbean, Scottish, Australian, Irish, etc. People say that the environment affects people a lot. So, living in a poor area, wealthy nation, with intellectual groups, with spiritual groups, different languages, etc. all affect people.
Stereotypes are there for a reason, they caricature other people. Y'know the whole Asians say L's for R's, well in Mandarin and Cantonese and I'm going to assume the other Chinese dialects don't have R sounds. Japanese have words with R's in them, but people either do or don't pronounce the sound. I think this might have to do where they live that affects why they don't pronounce it. That said, not all languages in Asian omit R's, in fact, Vietnamese and Thai have R sounds. My mom is Chinese, but lived in South Vietnam. So, she had two things with her accent: a Southern Vietnamese accent and a Cantonese accent.
In Vietnam, there are three prominent accents: Northern, Central, and Southern. Simply put, Northern stays true to original Vietnamese pronunciation; they don't omit any accents - as in the symbols on letters -, sounds, letters, etc. Southern deviates a little and is more lackadaisical. As for Central, I have no idea; I guess you could say Northern would be British English that's closer to what Old English was, Southern would be like American English, and Central is like Scottish English. Central puts heavy use on like one or two accents. Geographically, North is on it's own and Hanoi was the capital way back then when Vietnam had a monarchy and such. So, people spoke the King's Vietnamese so to speak. Central is on the mountains and I guess they were isolated so the way they spoke just became different and probably considered strange, rural, and uneducated. Funny enough, I think one of the previous capitals was in Central Vietnam. And then there's South Vietnam which is close to Cambodia, Malaysia, and was where the Cham people used to live. I'm going to guess that they picked up Cambodian, Malaysian, and Cham ways of speaking.
Going to my father, being South Vietnamese, he well, had a Southern accent, but he was also educated in a French school. What does this mean? Well, when he escaped to the United States, his accent was a mixture of French and Southern Vietnamese when speaking English. In French, H's aren't usually pronounced, and unless there's an E at the end of a word, you don't pronounce the "last" letter, plus other things. So, when he was on a bus to go to his brother, dad was looking for "Raymond Rd" as in "Ray-men". He pronounced it as something like Ramon or "Rah-moan". Unsurprisingly, the bus driver did not understand; dad had to write it down on a piece of paper. To this day and it can't be helped since he's old and learned English at a late age, my dad will still refer to English things or say them in French. Spark plugs are bougies and ham is usually jambon.
This obviously attributed to how I speak. In Vietnamese, since I learned to speak it, but never really got pass learning how to write and read - yay, I'm illiterate in Vietnamese - and since I don't use it everyday compared to English, I have a "bad" accent. I picked up my mom's way of not saying R's, I add English from time to time if I don't know the word in Vietnamese, and I have crappy grammar. It also doesn't help that I talk fast, meaning I slur words and stutter - I hope this does not get me in trouble with the law. I cannot speak Cantonese at all, but I can understand it, so there's that. English would be considered, generally, American English, however, I'm from the Upper Midwest, so I probably have a Midwestern accent. I don't know since I don't care or pay attention. That said, after listening to tons of people speak English in different accents, from Vietnamese, Indian, to general Britain, general Australian, Africa, etc., I might have picked up some little things from them. I don't talk much, but I listen a lot, so I definitely would have picked up random tidbits from people speaking English.
Also, it's kind of strange that despite getting a "proper" education in the United States, in French and most foreign languages, we learn more about grammar that in English classes, so I think that might be another reason since I learned to speak English just as I learned to speak Vietnamese while living with parents who rarely spoke English. I never really grasped the inner mechanisms of speaking English whereas in French, I learned what the rules were to speaking French even though I don't know how to speak it fluently. In English, it was just "Oh, this letter makes this sound and this is a vowel...". Whenever a random word comes up, let's say "Jacob", I'd mispronounce immediately. Guess what I thought it was. "Ja-cob", not "Jay-cub". Yeah. And then a French word like "raton laveur" (racoon) comes up and I can say it well; "rah-ton lah-ver". Another quirk is that I tend to say some things in their original language. Montréal usually comes out as "Mont-ray-al", the French pronunciation, instead of "Montray-al", the English pronunciation. This kind of makes me feel unintentionally pretentious. This also leads to me getting irritated when people mispronounce things like Toyota; it's "Toy-yo-ta", there's no freaking "I" that makes it "Tie-oh-ta". Also, I'm glad that Chevrolet made it clear that it's "Shev-roll-lay" - I would die if I heard "Chev-roh-let". Then there's jaguar, which I say "jag-warhr" or "jag-war". In England - don't know about Australia and other English speaking nations -, they say "jag-u-ar". Both are "correct". The British English follows English rules - I think that's an acceptable term. The American pronunciation follows the Portuguese adaption of the Tupi word "jawára" meaning large carnivore. If it were closer, it'd be something like "zhaag-war" since J's are pronounced like "Zh" sounds, apparently. Aside from those two, there's "jag-wire"... I don't want to explain why this is strange.
Anyway, with this long post, I think that the environment is the "cause" of accents. Living in a French-speaking, Afrikaans-speaking, Russian-speaking, or areas of a particular ethnic group or culture, or even an area with their own slang and speech patterns, all affect how someone speaks. For some of us, it might be funny, adorable, annoying, stupid, or just plain normal to hear a person say "Hello" in different languages and accents. I mean, there's "Hello",, "Hallo", "'ello", "Hullo", and the stereotypical "Herro". Or how about "Boston", "Baston", "Bostin", and "Bastin"? Personally, it makes this world interesting and personally, it would boring if everyone had the same accent, I mean, a Scottish accent is cool and all, but imagine if everyone spoke with a Scottish accent. It'd take away from the charm, annoyance, confusion, and novelty of a Scottish accent.