Many (if not all) of the Bush brothers have been reported as having learning difficulties, and it's quite possible he simply checked it by mistake. The depressing thing about this story is that clearly, these are the sorts of irrelevant things the media will spotlight, instead of actual policies:

Mr. Bush, a former Florida governor and likely presidential candidate, was born in Texas and hails from one of America’s most prominent political dynasties. But on at least one occasion, it appears he got carried away with his appeal to Spanish-speaking voters and claimed he actually was Hispanic.

In a 2009 voter-registration application, obtained from the Miami-Dade County Elections Department, Mr. Bush marked Hispanic in the field labeled “race/ethnicity.”A Bush spokeswoman could offer no explanation for the characterization.

Carolina Lopez, deputy supervisor of elections for Miami-Dade, said voters must submit hard copies of applications with a signature before receiving a voter information card confirming their address and polling location. According to the Florida Division of Elections, the application requires an original signature because the voter is swearing or affirming an oath.Florida law requires that the signature, driver’s license number and social security number be redacted before being publicly released.

While Mr. Bush’s claiming to be Hispanic may have been a careless mistake, confusion over heritage is no laughing matter during a campaign season.