Actress Ashley Judd was on “Good Morning America’’ on Thursday to talk about her new show, “Missing,’’ which is about a CIA-trained mom looking for her missing son. Judd told “GMA’’ host George Stephanopoulos that she based her character on a woman she met while studying at Harvard’s Kennedy School of Government. (Judd graduated with a midcareer master’s degree in Public Administration from the school in 2010.)