Her twin brother, Alex, quiet and independent, has always preferred getting out there and actually doing things. He is considering an apprenticeship in laboratory science.
Research shows that more parents see university as an important step for their daughters than for their sons, and the children are echoing those aspirations.
The Keable twins grew up together and share many friends. They both attend Moulsham high school in Chelmsford, Essex. But they are first to admit they are very different people.
Rachel said that doing well at school and university were very important to her. "Because women of my mum's generation didn't have such good opportunities," she said, "they definitely want us to grab them. Especially my mum."
Alex said he had always been less academically ambitious. "School has never quite been my way of thinking, the way I want my life to be."
Growing up, he had wanted to be a policeman, a fireman, and then a head chef. He has not ruled out university, though he is leaning towards an apprenticeship in a chemistry or biology laboratory.
Alex said: "University might give me more options for the future, but my style is more hands- on. I've never been too good at English so I try to keep away from writing long reports and focus on more practical work.
"I hope I will end up being able to stand on my own two feet."
Alan Smithers, professor of education at Buckingham University, says that girls made up 40 per cent of university students in 1980; today they constitute 55 per cent.
"When I was at school," he said, "girls were forced to leave at 16 because more education wasn't thought to be good for them. They needed to get practical skills and become secretaries until they settled down and got married."
Today, some boys, such as Alex, are getting positive messages about their capacity for practicality, innovation and entrepreneurship. But, overwhelmingly, boys are also getting discouraging messages about their academic ability, partly because of tests that favour female strengths.
That was why many boys and their parents were deciding that study was not for them, Professor Smithers said.
Mark Chaplin is managing director of Kirkland Rowell, the school evaluation firm that conducted the research. He said the findings posed a "chicken or egg" question: Are parents tailoring their aspirations to their children's abilities and ambitions, or are sons and daughters responding dutifully to their parents' desires?
Mr Chaplin said the findings suggested that the problem started early, with the messages parents gave sons and daughters.
For Rachel and Alex, it could be the influence of their mother, Laraine Keable. She left school after her O-levels on being told by her teachers and her mother that she was not smart enough to go to university.
Laraine said: "When I went back to work after having children, I realised what a mistake it was not going to university, because you go back in on the bottom rung. It's a tough old world out there."
How girls excel
GCSE In 2006, 54.6% of all boys achieved five or more A*-C grade passes; 64% of girls reached the same level; 88.3% of boys achieved five A*-G grades, compared with 92.8% of girls.
A-levels In 2006, 328,227 boys took the exam, compared with 386,976 girls; 96.6% of boys achieved grades A-E; 22.8% of them attained grade A; 97.7% of girls achieved grades A-E; 25.1% of them attained grade A.A higher proportion of girls than boys achieved grade A in all subjects except French, German, Spanish and non-mainstream science. A higher proportion of girls than boys passed in all subjects apart from non-mainstream social-studies.
In 2006-07, only 31% of university applications have come from boys. In the workplace, women earn 82.9% of men's pay.
What parents expect
67.7% of parents expect their daughters to attend university but only 60% expect their sons will.
66.7% of parents believe it is very important for their daughters to go to university - 61.5% for their sons.
79.9% of girls said they would like to attend university - 75.2% of boys agreed.
Parents' and pupils' university aspirations drop year by year as they progress through secondary school.
Scottish parents have higher university aspirations for their children than English or Welsh parents.
Source: Kirkland Rowell