Self-identity is based on memory. It is not based on blood linkage, political sense of belongings or historical linkage.
One’s self-identity is built within his limited lifespan. So it has nothing to do with the history a hundred or thousand years ago. His life experience is the origin to his identity, while the cultural and environmental context shaped such experience.
Natives and foreign mainlanders are of different nations. But when they cohabit together for two or three generations under the same environment, they form a new nation called the “Taiwanese”. What’s the point for blood linkage? You and I are both Taiwanese, not because of our ancestors; it is because of our same experience in childhood.
I was often irritated by those DNA theories. Those theories just reduce humans to apathetic bodies like animals. Even some animals have affections, don’t they? Cows, cats and dogs may have affections to humans when they live together for some time. Some foolish humans, however, use DNA, or blood linkage, to determine who are closer to them. What is the value of affection to such humans? It is exactly the reason why the World Wars broke out, thanks to such moronic theories.
From my point of view, the word “Chinese” is a cultural concept which means the “Sinic World” (with many variations in its name, e.g. “East Asia Cultural Sphere”, “Sinosphere” or “Confucian World”), which has nothing to do with geographical locations or blood linkage. A White or a Black who can write in Chinese and live like Chinese, is undoubtedly a “Chinese”. A guy born in the U.S. and grew up there, even his ancestors were from China, is considered an American. “Chinese” is a cultural concept, which should be mixed with geographical or genealogical factors.
“Han Chinese” (漢人) is a word which varies in its meaning throughout the span of Chinese history. Since the Ming Dynasty, the mindset of the Han Chinese was restrained by the authoritarian power; the situation was even worse during the Qing Dynasty. The thinking that “the one who has the power is always right” suppressed many ethical values.
“Han Chinese” is a cultural concept rather than a national one. The most objective definition of “Han Chinese” is: anyone who accepts “Imperial Examination” (科舉). For example, if a White is willing to accept the culture of “Imperial Examination”, he should be considered a “Han Chinese”.
“Han Chinese” is not a nation in strict academic sense. It is just a word assigned to a mass being conquered by a centralized power. Among this group of “Han Chinese”, they may speak different languages, with different ancestors and appearance. What they share in common is that they are ruled by the same great centralized power for a long period of time.
The current theory that prevails in China is: Your identity is determined by blood linkage. Who your ancestors were, then who you are. You are a “Han Chinese”, so your ancestors must either be “Han Chinese”, or they were converted as so. You have no choice of your identity.
Outside China, the theory is like this: your identity is based on self-identification and culture. The environment in which you grew up shaped you and nurtured your identification with that culture. The culture you identify yourself determines your identity. Though the environmental nature plays an important role, you may still choose your self-identification.