You're looking to compare the psychology of adopted Asian-Americans and un-adopted Asian-Americans? This is definitely a place where correlation can be a million things other than causation. I'm no social scientist, but two things come to mind right away:
Consider the financial situation of a household which adopts children - adoption is a very expensive and rigorous process, so adopted children of any nationality are going to be in a family which is financially secure and meets some kind of standard psychologically and legally. Not so for many Asian immigrants - I would imagine that on average, Asian immigrants aren't as well off as foster parents. Culturally, their environment will be quite different.
Cultural identities also come into play - adopted or not, Asian children will identify themselves as "Asian", just as Jewish children identify themselves as "Jewish", Russian children will identify themselves as "Russian", and African American children identify themselves as "Black".
Of course, none of this proves that there are no common genetic traits in the Asian gene-pool that help them excel at math, just as there are obviously genetic traits in the African American gene-pool which help them excel at running. Still, it doesn't mean much - the standard deviation in standardized math scores within any population is magnitudes larger than the difference in mean score between Asians and whites and blacks.
Consider the financial situation of a household which adopts children - adoption is a very expensive and rigorous process, so adopted children of any nationality are going to be in a family which is financially secure and meets some kind of standard psychologically and legally. Not so for many Asian immigrants - I would imagine that on average, Asian immigrants aren't as well off as foster parents. Culturally, their environment will be quite different.
Cultural identities also come into play - adopted or not, Asian children will identify themselves as "Asian", just as Jewish children identify themselves as "Jewish", Russian children will identify themselves as "Russian", and African American children identify themselves as "Black".
Of course, none of this proves that there are no common genetic traits in the Asian gene-pool that help them excel at math, just as there are obviously genetic traits in the African American gene-pool which help them excel at running. Still, it doesn't mean much - the standard deviation in standardized math scores within any population is magnitudes larger than the difference in mean score between Asians and whites and blacks.