The gender gap trend in student numbers starts as young as 13 when girls are more likely than boys to believe that going to university is important, according to new research.
Just 36% of boys enter higher education compared with 46% of girls, and Oxford University researchers found that even in Year Nine, when pupils are 13 or 14, girls have more positive attitudes towards university than boys.
The statistics may explain the growing disparity in university admissions between the sexes as aspiring to go on to higher education by 15 or 16 makes a big difference to A-level choices, a study published by The Sutton Trust showed.
Data from 3,000 young people found almost 65% of girls in Year Nine believe it is very important to go to university, compared with 58% of boys.
Over half of all the Year Nine pupils surveyed (61%) said it is very important to get a degree, compared with only 13% who said it is of little or very little importance.
About one in 10 girls feels it is not important to get a degree, but among boys the proportion declaring university of little importance is 15%.
Pupils aged 15 and 16 with similar GCSE results are twice as likely to go on to do three A-levels if they see university as a likely goal for them, and Professor Kathy Sylva, the report's co-author, said this could explain the gap in admissions later.
She said: "The higher aspirations of girls in comparison to boys may be linked to their greater A-level success and gaining admission to university."
The report also found that disadvantaged students are less likely to think they will go to university, with only 27% having high aspirations compared with 39% of their better-off peers.
The chief executive of The Sutton Trust, a foundation which promotes social mobility, called on schools to raise pupils' aspirations.
Sir Peter Lampl said: "We need to offer more support to disadvantaged young people throughout their education so that they are in a position to fulfil their potential after GCSE."
The Government said the attainment gap between disadvantaged pupils and their classmates has narrowed since 2011, and David Cameron has promised to double the proportion of disadvantaged young people entering higher education by the end of this Parliament, from 2009 levels.
A spokeswoman said: "We have introduced a more rigorous curriculum so every child, regardless of their background, learns the basics they need, such as English and maths, so they can go on to fulfil their potential, whether that's into the world of work or continuing their studies, and encouraging more young people, particularly girls, to study Stem (science, technology, engineering, maths) subjects."