It's really sad that they carried this "bad" act into secondary school. Read the lady's story below...
A lot of us have slept with our brother/sister while growing up. For me, I was disvirginéd at the age of 5 by my uncle.
After that, I started sleeping with my brother cause of the urge and when my uncle left for secondary school, I slept with my brother till I was in SS1 (when I realised that what I was doing is wrong).
Though then, my brother would still make moves trying to seduce me - for example he walks around the house with his manhood eréct or saying words like "if you want us to do it am ready".