Scientists have long asked why some otherwise normal children have difficulty in learning to read, but 650 research studies, which have converged on an intriguing and unexpected answer, have all but solved the puzzle. Most children who find learning to read difficult cannot distinguish the smallest sounds in words. They can hear these sounds but not separate them, which makes it difficult to link them to the letters by which they are represented. The ability to do this – which develops at about the age of five – is called phonological awareness. We are born with varying potential to develop this skill, which has nothing to do with intelligence.
The poorer the skill children inherit, the greater the problem in processing speech sounds and remembering them. Scientists recently discovered that our genes only start the story. What happens after birth is critical; it can cancel out a problem or make it worse: furthermore, it can cause the same neurological weaknesses that other children have inherited. Good parenting and good schooling will, therefore, reduce reading problems.
I'm not so sure that phonological awareness has "nothing to do with intelligence." Lack of PA skills correlates highly with low IQ. In any event, PA skills can be taught, but they are unfortunately not often taught well in most schools.