Technically, it's not possible for children to die from electrocution. This is probably an oversight by the developers. How Wilhelmina really died from electrocution is up to the player's imagination. She and Sandra Salas both died from electrocution. However, Sandra was likely born a Ghost baby and her parents both died of electrocution. She has pale green skin, grey hair and is barefoot like all the other deceased Sims of Twinbrook.