Year 7 girls have been warned not to have multiple sex partners or risk becoming like overused sticky tape, in a Christian sex education program at a public Victorian high school.

The students at Fairhills High School, in Knoxfield in Melbourne's outer east, were also told that a chemical released in females' brains made them more needy than boys.

It is hardly unknown for teens to have sex before adults think the time is right.

A booklet titled 'Science & Facts', that was given to the students, said that "girls are needier than guys in a relationship and always want to be close".

It said that a chemical called oxytocin, is released when "two people touch", and was produced by women more than men, making them needier.