Hiring more men as teachers may be bad for boys' education despite a drive to provide male role models in schools, Government research warns.
Ministers want to increase the number of men in the classroom in an attempt to help boys work hard and achieve better grades.
But a report by Schools Department officials said there was little evidence that this "simplistic" approach would work, and suggested that men could be too "harsh" on boys.
The study also found that there was "no case" for adopting "boy-friendly" teaching methods in an attempt to close the gender gap.
The report, Gender and Education: The Evidence on Pupils in England, said 84 per cent of nursery and primary school teachers were women.
"The increasing gender imbalance in the school work force has raised concern that male role models are not available to boys," it said. "The fact that policy efforts have been made to address this imbalance reflects the theory that having more male teachers could help to raise the attainment (and/or improve the behaviour) of boys. However, this approach has been criticised as simplistic."
Researchers found last year that two-thirds of pupils rejected the idea that the gender of their teachers mattered. "Moreover, there is very little evidence to date as to whether a teacher's gender does or does not play a significant role in their pupils' attainment," the study said.
The report cited more research which found that older pupils thought men were harsher on boys than women.
The findings cast doubt on calls this year by Alan Johnson, while he was education secretary, for more men to work as primary teachers and suggesting that lessons should be fast, practical and factual to grab the attention of boys.