Unhappy childhoods are each unhappy in their own way. For Hansel and Gretel, things look grim but turn out sweet; for Elektra... not so much. Hear both stories in great German operas this Saturday from the Lyric Opera of Chicago: Richard Strauss's Elektra, with Christine Goerke in the title role, and Engelbert Humperdinck's Hansel and Gretel, with Elizabeth DeShong and Maria Kanyova as the siblings and Jill Grove as the witch.