In Jerusalem, that ancient and holy city, people’s houses are built on bones. For thousands of years, hundreds of generations of Jews, Muslims and Christians have been laid to rest in its rocky soil. Tova Bracha has always known that the tiny, rose-bordered concrete plot next to her apartment building covers an ancient Jewish burial tomb, but she never thought much about it. “It just didn’t seem important when there are so many tombs anyway that have been found around Jerusalem,” she says. Rushing home for the Sabbath, her arms full of groceries, Bracha laughs at the suggestion that the tomb might be of considerable religious interest. Maybe she can make a fortune selling trinkets to tourists, she jokes. Maybe the value of her home will soar.This week the Discovery Channel, together with HarperSanFrancisco, announces the release of “The Jesus Family Tomb,” a television documentary and a book that aim to show that the tomb next door to Tova Bracha’s apartment, located in a nondescript suburb called East Talpiot, is, well, the family plot of Jesus Christ. Spearheaded by a well-known TV director named Simcha Jacobovici, and produced by “Titanic” director James Cameron, “The Jesus Family Tomb” is