T here was danger outside the gate, we understood that. You could see it.  Precariously balanced on the very tip of Coney Island, Sea Gate, where I was raised, is surrounded by water on three sides and divided from the rest of the world by a two-story chain link fence. The fence, broken up only by two actual gates manned by guards, stretches three-quarters of a mile along 37th Street, from New York Harbor on the north side to the Atlantic Ocean on the south. On our side of the fence, tree-lined streets. The closer you get to the ocean, the bigger the houses. From the beach, a view of the Verrazano Bridge. In the 1890s, the Vanderbilts, Dodges, and Morgans built houses here. In fact, some of the houses on the beach were 40-room mansions before they got divided up during the Depression. It was a private beach escape for the rich. You can understand why they fenced the neighborhood off. On the other side of the fence, where today stand residential high-rises, were slums.…