Why is it that ADHD seems to “fade away” with age, thus affecting youngsters more? I thought if a problem is genetic,

Question: Why is it that ADHD seems to "fade away" with age, thus affecting youngsters more? I thought if a problem is genetic, as suggested with ADHD, then it would be adopted for good.
- Keywords:
  adhd,
  child
Asked by guesswork to Simon on 17 Jun 2011.
- Simon Trent answered on 17 Jun 2011:
  
  ADHD is a developmental disorder, meaning that it araises in children, normally around 5 years of age. A proportion of these children will continue to have ADHD when they are adults and this can be a serious problem for holding down jobs and relationships etc. With age and normally help from ADHD drugs, adults seem to control the symptoms of ADHD better, but its not to say its faded away.
  
  About the genetics, ADHD is PARTLY genetic, and also occurs for lots of other reasons that might be to do with the envirnoment (eg. whether your mother smoked when she was pregnant) or it might be a combination of environmental factors interacting with certain genes.

Question: Why is it that ADHD seems to "fade away" with age, thus affecting youngsters more? I thought if a problem is genetic, as suggested with ADHD, then it would be adopted for good.