Probably not as many who would be high fiving their 15 year old son if he had shagged a 28 year old teacher. In fact they would probably be asking if he had any pictures of her with her kit off, and offering to make the teacher gas tight the next time the son was boffing her.
Don't get me...
Whilst I can understand you rightly wanting to protect your daughter, would you do the same and kill the other partyif your 15 year old son shagged his 29 year old EDATOS female French teacher?
I think teachers don't need such discouragement, it would not enter the heads of 99.9999% of them because they are not that unprofessional/stupid/ugly (delete as necessary).
Relationship with an undergraduate would not be allowed. If caught you would be sacked on the grounds of gross moral turpitude. There would not be a criminal case though, as the people involved would be above the age of consent. Things get a little murky though if it is a postgraduate student...