I make my sister give me oral sex behind our parents' backs, and share my thoughts in my diary. I've taught her since we were little that oral sex is a normal thing for siblings, and she still believes it. My sister's oral sex techniques are improving every day! Lately, she's become even more erotic, and she's escalating her act, giving me oral sex when our parents can't see! It's seriously dangerous! But the thrill of not being found out by our parents, who are right next to us, is what gets me excited to the max! We end up crossing the line, and with no way to stop, we're immersed in incestuous relationships... To my sister, it's something that any brother or sister would do, so she doesn't question it at all. But knowing the truth, I honestly feel a little guilty.