Current scientific consensus shows that AD/HD is principally a
genetic, inherited medical condition. This means that many
families have a parent or close relative who has similar
problems. Sometimes a parent may show the condition more
severely than the child and vice versa (Alban-Metcalfe & Alban-
Metcalfe, 2001). Twin studies suggest a 90% concordance rate in
mono-zygotic twins. In other words, if one identical twin has
ADHD there is a 90% chance that the other twin is also affected
(Myttas, 2004; ADDISS, 2004; Knivsberg, Reichelt, & Nodland,
1999). Further, if there is one child that has ADHD in the
family, there is a 30-40% chance that other siblings may also
have the disorder (ADDISS, Prevailing research has shown that
individuals with AD/HD compared with those without AD/HD have
‘under-active’ parts of the brain under specific test
conditions. Modern brain scans (PET and SPECT) have shown that
there is less brain activity, particularly in the frontal area
of the brain. Studies have shown decreased amount