U.S.-born children of Mexican citizens whose parents were born in Mexico are, in fact, Mexicans -- that is citizens of Mexico [0] -- as well as Americans -- citizens of the United States. (Tangentially, the same is also true of Mexican-born naturalized citizens of the United States, who remain Mexican <i>nationals</i> unconditionally, and remain Mexican citizens -- notwithstanding the US requirement to renounce foreign citizenship -- unless they take certain actions specified in Mexican law by which Mexican citizenship can be lost.)<p>So counting them in the net migration of Mexicans into and out of the US is quite appropriate (as would counting them in the net migration of <i>Americans</i> into and out of the US, were that the subject under discussion.)<p>[0] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Mexican_nationality_law" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Mexican_nationality_law</a> ; though they may face significant bureaucratic obstacles in establishing this if care was not taken by their parents prior to their return [1]<p>[1] <a href="http:&#x2F;&#x2F;www.huffingtonpost.com&#x2F;2012&#x2F;07&#x2F;18&#x2F;us-born-children-migrants-lose-rights-in-mexico_n_1683704.html" rel="nofollow">http:&#x2F;&#x2F;www.huffingtonpost.com&#x2F;2012&#x2F;07&#x2F;18&#x2F;us-born-children-mi...</a>