So this chart strongly suggests that we should seal the borders and chose only from the Chosen as the optimal immigration policy?

"In 2013, over 40 million foreign-born representing 13% of the population resided in the United States." - http://www.brookings.edu/blogs/brookings-now/posts/2013/09/w... . See also https://www.census.gov/newsroom/pdf/cspan_fb_slides.pdf .

Using that as a baseline (though it has changed over time) means the probability of having at least one foreign-born parent is 25%.

Of the remaining 75%, the probability that at least one of the grandparents is foreign born is 42%.

0.25 + 0.75 * 0.42 = 56% chance that someone in the US is a 1st or 2nd generation immigrant.

Sure enough, "60% of top 25 tech companies founded by 1st and 2nd generation immigrant" is almost exactly what's expected if a company is founded by a single person.

BTW, the table contains at least one error. It says that William Hewlett is not a first or second generation immigrant.

William Redington Hewlett's father was Albion Walter Hewlett. (http://www.hewlett.org/about-us/hewlett-family-history/willi... says that William was born in 1913 and the family moved to California in 1916 so his father could work at Stanford. http://medicine.stanford.edu/faculty/hewlett.html says "Doctor Albion Walter Hewlett, professor and executive head of the Department of Medicine from 1916 -1925".)

The 1910 census record says Albion and his wife were born in California. https://familysearch.org/ark:/61903/1:1:MLTH-RKY . It also says Albion Hewlett's father was born in England.

Therefore, Hewlett is a second generation immigrant.