London: Facing problem in solving puzzles, sums or quizzes? Well, blame your parents for it.

Researchers have found that up to half of our intelligence (or lack of it) is inherited.

They examined the blood of more than 3,500 people from England and Scotland for half a million genetic markers -- tiny changes in their DNA.

Analysis of these results and those of intelligence tests completed by the study's participants revealed that 40 percent of the differences in "crystallised-type intelligence", the ability to acquire knowledge and skills over the years, were in the genes.

So-called fluid-type intelligence, the ability to reason and think abstractly under pressure, was governed by genetics to an even greater extent. Some 51 percent of a person's ability to "think outside the box" is down to DNA.

"Individual differences in intelligence are strongly associated with many important life outcomes, including educational and occupational attainments, income, health and lifespan," lead researcher Professor Ian Deary, of the University of Edinburgh, was quoted as saying.

However, he added that the study's results "unequivocally confirm that a substantial proportion of individual differences in human intelligence is due to genetic variation".

The study has been published in the journal Molecular Psychiatry.