I cannot believe some of the posts on here. By analogy you are saying that if an 11 or 12 year old girl has gone through puberty, a man having sex with her would not be a paedophile!
Obviously, as a civilised society, we protect all children from under age sex. It is the people who enable this criminal in his life that are often at fault as well. Bringing up a son as a little emperor who can do no wrong has produced a liar with no regard for the law who indulges his every whim at the expense of others.
The evidence suggested that he targetted other pupils at the school, not just this one. He used his position as a teacher to manipulate children going through hormonal changes which made them vulnerable.
To suggest that he was the victim if some lolita he lacked the power to withstand is ridiculous, as are his sister's comments which implicitly blame his wife, who was lied to and cheated upon.
I have no doubt that the way his family brought him up contributed to his appalling beahaviour.