Nearly half -- 46pc -- of 13-year-olds discuss sex and relationships with their parents.
And mothers were the preferred confidante, with only 6pc saying that they would go to their fathers.
The findings were revealed in the latest Growing Up In Ireland study.
When it comes to confiding in parents, girls find it easier to open up, with 51pc happy to discuss sex and relationships, compared with 41pc of boys.
But it was not all bad news for fathers: teenagers say that, while they find it easier to talk to their mothers, they have more fun with their dads.
The changing face of Ireland can be seen with the revelation that, over the past four years, 4pc of the youngsters have gone from a two-parent to a one-parent family: one in five 13-year-olds now lives in a one-parent home.
Alcohol use among young people continues to increase, with up to 15pc of the 13-year-olds admitting to trying alcohol.
Similar numbers of boys and girls had sampled alcohol, while just over 0.5pc said they drank once a month or more.
The wide-ranging Growing Up In Ireland survey documented 7,400 13-year-olds and their families, focusing on health, education and lifestyle.
The results provided a stark reminder of families' bleak financial situation in the run-up to next week's Budget.
Six in 10 of the children are in families who are finding it difficult to make ends meet.
And the young people say that their family's financial circumstances have deteriorated since the last time they were surveyed.
Obesity among young people is another area of concern as one in four 13-year-olds is now overweight or obese.
And the study revealed that more than half of those who had weight problems four years ago have not shed any pounds.
In fact, 11pc of those who were overweight when they were nine are now obese.