yes she did. Shortly after her 24th birthday in November of 1959 she had a daughter Maria Tinney. Several years later she had a miscarriage. Her daughter had two sons in the late 80s and early 90's.
Yes he did. While making Call of the Wild with Loretta Young in late 1934 they had an affair and Loretta became pregnant. She had a baby girl named Judith in November 1935.
No Clark Gable never acknowledged his daughter by Loretta Young. He did visit her several times during her life though. When she was an infant he went to visit her and gave Loretta Young 400 dollars...
He had four step-children by two wives. His second wife Ria Langham had a daughter and son by previous marriages and his fifth wife Kay Williams had a son and daughter by her previous marriage.