What started this flux? For more than a decade, we’ve lived with personal technologies — video games and social-media platforms — that have helped us create alternate or auxiliary personae. We’ve also spent a dozen years in the daily grip of makeover shows, in which a team of experts transforms your personal style, your home, your body, your spouse. There are TV competitions for the best fashion design, body painting, drag queen. Some forms of cosmetic alteration have become perfectly normal, and there are shows for that, too. Our reinventions feel gleeful and liberating — and tied to an essentially American optimism. After centuries of women living alongside men, and of the races living adjacent to one another, even if only notionally, our rigidly enforced gender and racial lines are finally breaking down. There’s a sense of fluidity and permissiveness and a smashing of binaries. We’re all becoming one another. Well, we are. And we’re not.