Deborah Treisman, left, and Silvia Killingsworth of The New Yorker review a mockup of the new fiction issue.Credit...Ruth Fremson/The New York Times There are 10 women and 10 men, satirists and modernists, from Miami and Ethiopia and Peru and Chicago. And none of them were born before 1970. The New Yorker has chosen its “20 Under 40” list of fiction writers worth watching, a group assembled by the

