31/01/2012 14:56 GMT | Updated 22/05/2015 06:12 BST

Want Clever Kids? Have Them Two Years Apart

Baby and two-year-old sibling Alamy

The simplest way to have smart kids is to have them two years apart, according to a report.

Instead of spending a fortune on private tutors, educational DVDs and bucketloads of brain-boosting fish, the best way to give your kids a head start is to resist your urges until the time is right.

Having children two years apart is the optimum way to nurture cleverness in children. If the gap is smaller, the reading and maths skills of the older child suffer.

Economist Kasey Buckles came up with the theory for the University of Wisconsin's Journal of Human Resources. The mum of two – whose own children are just over two years apart in age – believes academic achievement is linked to the time and resources parents can invest in a child before number two comes along.

But she said that waiting more than two years didn't increase the advantage.

"We believe this is the first time anyone has established a casual benefit to increase the spacing between siblings," Buckles told the Sunday Times.

The study also showed that gaps between children in larger families was also beneficial.

"The two year gap is significant because the early years are the most important in a child's development so dividing your time when the child is one is more harmful than dividing it when the child is already at school," she said.