Young boy never knew his mother. Had heard stories of how she left when he was a baby. Then on his 18th birthday he has sex with his older sister. Against her original wishes he cums inside her. Later they find out that she is pregnant from their time together. She has sex with him again and tells him the truth about his mother. She is actually his biological mother. She had sex at a young age and got pregnant. Her father took him in and claimed him as his own. Any stories that are similar to this out there?