The calculated grading system being used for this year's Leaving Certificate has been designed to ensure that overall girls will do better than boys.
The exams system is supposed to be blind and anonymised, but the gender of students will be taken into account, the Irish Independent has learned.
It could yet become a battleground over the estimated results, which are due to be issued on September 7.
In England, the issue of predicted grades is now a major controversy.
Students vented frustration at a system that has already seen 40pc of final-year A-level students receive lower grades than those predicted by their teachers.
In Irish schools, girls consistently perform better than boys on average during the end-of-school examinations.
Education Minister Norma Foley's admission that the gender trend would be factored into the calculated grades system came in a little-noted parliamentary reply just before the Dáil rose.
"The use of demographic characteristics, including gender and socio-economic status of the school, was inherent in the Technical Working Group's design of the calculated grades model," Ms Foley admitted.
Separately, the challenges facing schools preparing to reopen under Covid-19 restrictions are laid bare in figures that show Ireland has the most overcrowded in Europe.
There are 335,649 pupils in of 25 or more, and almost 100,000 in super-sized of more than 30.
Ms Foley said in her written reply to Sinn Féin TD Donnchadh Ó Laoghaire: "The purpose of the calculated grades system is to arrive at the grade each student would have achieved if the Leaving Certificate examinations had taken place as normal.
"Students' expected performance in a subject and level is combined with information about how students in the school have fared in this subject in recent years, and with their performance at Junior Cycle."
The outcome would be "as reasonable, fair and accurate to students as possible".
In order to make sure that the standardisation process works, there will be validation - including any necessary re-balancing to preserve girls' advantage on higher grades, as seen in previous years.
"Validation serves to ensure that the statistical standardisation process is presenting results that are as fair and equitable and in line with previous outcomes as much as possible," Ms Foley said.
But Mr Ó Laoghaire said: "While this may seem academic to some, the reality is that this will affect whether countless students get the course of their dreams or not.
"It will affect whether they fail a subject or not. This matters enormously, and students from disadvantaged backgrounds should not suffer because of past results.
"The minister needs to publish the model, and outline what weighting is attached to social background, school results and gender. We also need to be now considering options as to how the problems that existed in Scotland and elsewhere can be eliminated."
He added: "We've been raising significant concerns regarding school profiling or 'standardisation' for months now.
"Unfortunately the experience elsewhere has increased our concerns, as students have been held back by the past results of their school, rather than being evaluated on their own merits.
"Neither nor gender should define whether a student gets an A or not, nor whether a student fails or not."
Labour's spokesman on Education, Aodhán Ó Ríordáin, said his party had always resisted cancelling the exams because "we didn't feel that it could be replaced by a fairer system".
According to Mr Ó Ríordáin, one of the only strengths of a rather unfair and unequal system was that "somebody can be absolutely anonymous when they walk into a into an exam hall".
He added: "They put down their exam number and we don't know who they are, don't know where they're from."
A document called 'Data Collection National Standardisation and Quality Assurance' on the Department of Education website confirms the pro-female bias.
It specifically declares: "In the case of gender, if the performance of female students relative to male students in various subjects turns out to be similar under the calculated grades model, as was normally the case in previous examination years, then this can be taken as an indicator that the model is in line."
But the Department of Eduction defended the gender and socio-economic 'validation' measures, saying: "Not to run these checks would run the risk of not being able to tell whether or not the standardisation process was working to ensure that the Leaving Certificate results of 2020 are properly comparable with Leaving Certificate results in any other year."