Dumbledore has been destroying his students
It seems that Albus Dumbledore has given all his 7th year students, the year that now resides the 'Boy-who-killed-he-who-must-not-be-named', a potion that stops any creature inheritance.
He clames that it was for the greater good and no one should go against what ever he says. He is the headmaster of Hogwarts. He says that any creature inheritance would destroy what he wanted in the school and changed all 1st years, 7 years ago, so that they would be normal and strong.
All 7th years are to take the counter potion that would destroy what the ex-headmaster has givin them. Whatever they turn out to be, they will stay at the school and get the education. Everyone should go to the school nurse to obtain this potion. If they do not take it, it is possible that they will be driven crazy and might even die.
History of Albus Dumbledore page 4
How this potion might have to do with He-who-must-no-be-named page 6
Other possible conditions of not taking the potion page 8
I am trying out a new story.