A former classmate, whose ancestors came from Fujian for several generations long before 1949, showed us his upper left arm in a recent gathering and we found there is a clear horizontal crease near his elbow.  Then several other classmates who has the same family background as he all found they have the similar creases, whether conspicuous or not.  Now it was my turn: there is no crease at all, and the skin of my arm is comparatively less darker than theirs.

The classmate, a retired professor, revealed the "secret" to us.  The earlier immigrants from Mainland were single males only.  Those pioneers had to find the aboriginal girls in the plain areas as their mates.  The couples then produced their hybrid offsprings who had carried the gene of aboriginal islander since.  The crease is one of the "charcteristics" to distinguish people between the immigrants who came to Taiwan before or after 1949.  (I have also heard of that there had some other "charcteristics", e.g. different foot toes.  And all of these "evdences" have long been used by Taidu advocates as they are of different "racial group" from Chinese, and they are bound to be a new nation so as to build up a new country.)

But I have to tell you guys that the blood is never a determinant of whether you are Chinese or not.  It is rather the recognition to Chinese culture that really matters.  I am not sure if my ancestors have mixed with other "barbarians" how many times before, but that would definitely not prevent me from recognize myself as a genuine Chinese.