Baratunde nails it here. Do yourself a favor and take the 7 minutes to listen to what he has to say. This is about race, not nationality or origin.
A short opinion piece on CNN calls this out as well:
It’s no surprise that Donald Trump, the quintessential example of bloated, egocentric American wealth and excess, has already moved on to questioning the grounds for President Obama’s admission to Harvard. No rational person doubts the intellectual gifts of the president. They’ve been on display for decades. It’s hard to imagine a movement demanding proof that President George W. Bush was admitted to Yale or to Harvard Business School on the basis of his academic performance. The point is not to question Obama’s intellect. The point is to suggest illegitimacy.
Sad to say, but I got a tiny view into the racist “birther” viewpoint when I was back in Upstate NY from my father. I squashed that one real quick, but it’s obvious that this is very common throughout the country. Terrible.
(Source: jackandjillpolitics.com, via buchino)