In the new movie “Delivery Man,” Vince Vaughn discovers that his “donation” has been used hundreds of times without his knowledge. Far-fetched plot? Maybe not. The United States does not track sperm donations. We have no idea how many there are, how often they're donated, nor how many children are born from those donations. Rene Almeling is an assistant professor of sociology at Yale. She wrote an op-ed piece for the New York Times about “The Unregulated Sperm Industry.”