Have you got any evidence for this, STEM tests at the border? 
And why would not the same effect play out with hispanics?
And why do 2nd and 3rd generation asians so utterly dominate STEM subjects at elite US universities that there are de-facto quotas to limit asians?<p>But most of all, how did those  Indians and Chinese acquire those superior STEM skills without access to the educational resources that are given to all US citizens?