When I was 24, a stranger on the internet called me a white man, and it sent me into such a tailspin that I changed my byline. Before then, I was going by “Alex Laughlin,” just my first and last name. I had started writing about race, and I’d made a podcast about multiracial identity called _Other_ , but if my name was to represent me on its own, there was no way for a stranger to know that very…