Teenager Amie Bartram was back at school this week after being suspended for three days for "sexually harassing" a trainee teacher.
The 14-year-old was sent home from Hellesdon high in Norwich after she allegedly ripped open her blouse in front of Paul Chant, a technology teacher.
Bill Gould, head of the specialist technology college, defended the suspension, and said: "Pupils need to take responsibility for their actions. If it had been my daughter I would have been mortified."
Amie was in a detention with other pupils when she asked the 32-year-old teacher for help with some homework, he said.
Mr Chant asked Amie to fasten the top buttons on her blouse first, but, according to Mr Gould, she said she was wearing a T-shirt underneath and ripped her blouse open to the navel to prove it.
Amie, who returned to school on Monday, said she merely told Mr Chant she had a T-shirt on underneath her blouse and was about to fasten her buttons.
Her parents said the sexual harassment allegation was false and fear the suspension has jeopardised her career chances.
David, her father, said: "My main concern is that this stays on her school record. She wanted to be a physical education teacher. She had also considered childcare or care work of some kind.
"The school is victimising Amie. Last year she was suspended for three weeks for missing a Saturday detention. I said she didn't have to go to."
Mr Gould said the suspension would not affect Amie's career: "It will be on her file until the day she leaves. Amie's parents' fears about her career are unfounded."
Amie's mother Sharon, said: "I will not have my daughter classed as a sexual harasser. Amie's outspoken and says what she thinks, but sexual harassment is a big word and inappropriate to use about a 14-year-old.
We're going to push to get the words 'sexual harassment' dropped from her record."
Mr Gould refused to alter his stance: "It was the right decision and I'm not going to shift on it.
"Naturally, Mr Chant was embarrassed by Amie's inappropriate behaviour. We have a rule that says only the top button of a girl's blouse can be open.
We have had incidents where girls have had too many buttons open and boys have responded in the way boys do when they see lots of flesh."