One school principal says people would be 'appalled' if the idea of single-sex schools was implemented today.
Simon Lewis, principal of Carlow Educate Together National School, was speaking as the Government is being urged to end single-sex schools within the next 15 years.
Labour's Aodhán Ó Ríordáin says co-ed schooling is already 'de facto' policy, and his party now wants a timeline put in place to phase out single-sex schooling entirely.
His party is publishing a bill this week which aims to bring an end to gender discrimination in school admission.
Mr Lewis says Ireland is an outlier on this.
"Co-ed schools are - I guess normal is the only word I can use - and single-sex schools are just abnormal internationally.
"So he's absolutely got then right idea."
And he says this is not as much about academic outcomes as other issues.
"Our educational outcomes seem to be quite similar whether we're single-sex or not.
"The problem comes down to outside of educational outcomes, and I think that's possibly more problematic.
"So you might do just as well in a single-sex school as you would in a mixed school, but - for example - a child who may be identifying as a different gender is definitely going to suffer in a single-sex school."
Mr Lewis believes if the suggestion of single-sex schools was made today, "I think people would be appalled.
"But just because it's so normal for us we just seem to accept it.
"And when we look at Ireland internationally, we're so far removed from everywhere else... it just makes no sense to have it."