First-born children are given 3,000 hours more quality parent time

They may not realise that they are doing it, but parents spend an extra 3,000 hours of quality time with their first-born child than with subsequent children.

First-born children perform better at school and even earn more money later in life as a result of the added attention, a study claims.

The findings are likely to surprise families who believe they are treating all their children equally, regardless of age.

The study found that parents do appear to spend approximately equal amounts of time with all their children on any particular day.

However, when the total number of hours spent with each child between their fourth and 14th birthdays is totted up, the younger siblings lose out by around 3,000 hours, or 125 days.

Joseph Price, economics professor at Utah's Brigham Young University, conducted the analysis, which appears in the new issue of the Journal of Human Resources.

He studied data from the American Time Use Survey, a federal government study involving 21,000 people, and compared hours spent by families on their children.

Professor Price believes the difference is because the amount of time parents spend with children on a daily basis declines as families get older.

First-born children get more attention simply because they pass through childhood when there is more overall family time to be shared.

The professor also found that parents not only spend fewer hours with their younger children, it is less likely to be "quality time."

These children watch more TV with their parents between the ages of four and 13 than their elder brother or sister did during the same time period, instead of joining together for more rewarding activities.

Professor Price concluded that the size of a family did not affect the amount of quality time given to the youngest child.

He said: "We've known for a long time that eldest children have better outcomes and these findings on quality time provide one explanation why.

"If your goal as a parent is to equalise outcomes across your children, you should be aware of this natural pattern and try to give younger children more quality time."

Suzanne Bianchi, a sociologist who studies time use, said: "The study convincingly demonstrates that parents spend more time with their oldest child - probably largely without realising it or intending to treat their children unequally."

Some might say the phenomenon has proved itself in celebrity circles. Kylie Minogue's younger sibling Dannii has always struggled to match the success of her sister.

While Kylie has sold millions of albums worldwide, Dannii is now better known as a judge on The X-Factor.

Likewise, while Sir Mick Jagger is among Britain's wealthiest rockers and regularly sells out stadium tours, his younger brother Chris, also a musician, has to be content to play guitar to more humble audiences, mostly made up of curious onlookers.

Research from the United States has found that older children tend to be better educated and score higher on IQ tests.

And a UK survey of 10,000 men and women revealed that oldest siblings are more likely to do well in exams, with the first-born in a family of two achieving the highest grades in the majority of cases.

The study from the Institute for Social and Economic Research at Essex University found a clear link between order of birth and exam results.