As the son of one American immigrant and the father of another, I find it hard to muster much empathy for Facebook co-founder Eduardo Saverin and his decision to renounce his US citizenship. Saverin, who was born in Brazil and brought to this country as a child, turned in his American passport last year and moved to Singapore; it is widely assumed that he did so to reduce the taxes he would otherwise have to pay on the billion-dollar gains generated by Facebook’s IPO. Saverin denies, not very convincingly, that his expatriation was motivated by tax considerations. “His decision had nothing to do with dissatisfaction here,” a spokesman said, “but with his strong desire to do business there.”