My MC's mom is English, and his dad is American, but his dad's parents are English. What would this make him? Is he completely English or would he be English American or something? He was born in England, but lived most of his life in America. When this comes up in the story, I don't really know what to call him. Also, I believe he would have dual citizenship. Is this correct?
I don't know about the citizenship thing, but I'd probably categorize him as American. If his mother's national culture is important to her and something he was raised with, then he might consider himself British (?) American. As far as legality/citizenship goes, I googled and found (source):
Legally it will depend on whether he took out US citizenship (or whether his father's confers the same on him, check immigration laws on that). How he feels is part of what you create - me, I was born in England of British parents, came over to Australia as a child, and now have dual citizenship: I call myself Anglo-Australian (the dual was very handy when travelling in the EU, but that will now probably change)
I'd consider him American. He grew up there, likely has the accent, is tuned into that culture. He might be more familiar with British culture than most other Americans, but that's all. Also, it seems he'd be eligible for dual citizenship, according to this site: http://immigration.findlaw.com/citizenship/dual-citizenship.html Born outside of the US to one parent who is a US citizen and another who's a citizen of another country.
Here's a parallel. My co-worker was born in England, then moved to Canada as a young child. He has no accent and has dual citizenship. He considers himself Canadian, and has Canadian outlooks (for which he is sorry). He still visits England every couple of years, so he still maintains a kind of spiritual connection to the UK. In the case of your protagonist, he will very likely consider himself to be American, though he will also have some English elements to his personality-- maybe a stiff upper lip or predilection for spicy mustard.
The United States won't recognize dual citizenship. The U.K. will recognize dual citizenship, though. My parents' retailer just had his children not tell the U.S. that they also have U.K. citizenship. Regarding your main character, because he was primarily raised in America then he would likely think of himself as American. He could consider himself English-American, but that might cause people to give funny looks though it makes sense if he has dual citizenship. It all really depends on how he was raised and what he was taught to think about the U.K. For example, I'm U.S. American, but I grew up military and I don't consider the U.S. home. In my own personal thoughts I'm not really anything and my family incorporated a lot of traditions from Italy and England into their lives. If I were to write about myself I would never refer to myself as an American.
Why the answer is so obvious, he is clearly Chinese. The US does recognize dual citizenship, but it helps if they were a military brat as they are still considered American while born on post in a host country, but can still apply for citizenship in the host country. Should technically apply for those on vacation as well, if a tourist and a local conceive and bear a child. Though it may be a bit more complicated as to the nature of their status of citizen may be in the country where they are birthed, but may be able to apply for dual citizenship with both countries of each parent. (IDK really, so this is just a guess.)
Formally, the U.S. doesn't appear to recognize dual citizenship because it's not written in law. They won't make you give up your nationality in another country, but being a dual citizen can put you at risk of the U.S. not being able to help you legally. The U.S. Department of State - Bureau of Consular Affairs wrote up a small blurb about it. It's kind of a wishy-washy territory to be in, at least if the other country's laws don't jive with the laws of the U.S. As for dual-citizenship regarding the host country if born on a military base, it depends on the country. Some countries will grant you citizenship from right of birth while others require a more strenuous process. Germany will recognize you from birth while the U.K. won't if you were born after 1983 and don't meet the following criteria: (from Gov.uk) The UK Visa Bureau also lists the requirements, the majority of which require living in country excluding from 1961 to 1983. Overall, military brats can't apply for UK citizenship unless a parent is British because U.S. military parents don't have a right to permanent residency in that country (their stay has a time limit). On the other hand, the U.S. will take you if you're born on U.S. soil even if your parents aren't citizens. [This post looks a lot longer than it is; I'm sorry. Dual citizenship is just a curious beast and each country is different regarding it.]