Tiny genetic changes are responsible for almost half of the variation in height between individuals, scientists have announced.

Genetic inheritence accounts for about 80% of height variation in humans, while factors such as nutrition determine the rest.

But scientists have only found genetic changes accounting for 5% of the variation, leaving them puzzled over where the rest come from.

Now researchers publishing their results online today in the journal Nature Genetics say they have found this 'missing heritability'.

They say that changes in single 'letters' of the genetic code - known as single nucleotide polymorphisms, or SNPs - actually account for 45% of the variation, not just 5%.

The scientists, led by Professor Peter Visscher, a geneticist at the Queensland Institute of Medical Research, analysed the DNA of almost 4000 people.

Instead of looking at the SNPs individually, they analysed them simultaneously, ensuring that SNPs with small effects on height were also included.

"We found that the majority of genetic variation for height is indeed [associated with SNPs] it's just that the size of the effects of individual changes is very small. There is no 'missing heritability' which some people have argued ... it's just been hiding," says Visscher.

Some SNPs have effects as small as a millimetre, he says.

The researchers think that the remaining variation is probably caused by rarer SNPs, and that these will be found with larger studies looking at many thousands of people.

Scientists aren't just interested in the genetics of height for its own sake. "We look at height because it's a nice model complex trait," says Visscher. "It may point to what is going on with diseases."