Abstract: Mental retardation has been the traditional foothold of psychologists and psychometricians, apart from clinicians and biologists. Nearly 30,000 genes control neurogenetic disorders. While these genes are yet to be explored, their ultimate expression and regulation defies a mechanistic model of behavioural and intellectual deficiency. Mental retardation, therefore, will be a complex problem to be diagnosed and cured. A polygenic theory demands delineating Quantitative Trait Locus (QTL) problem, yet to be formulated among humans. At the molecular level, molecular genetics of neurological disorders have been worked out. Taking from basic roots of neuronal functioning and their integration at various levels of the central nervous system, the mutations of neuronal channelopathies resulting into loss of brain function (seizures, convulsions, epilepsy), uncontrolled muscle movement (ataxia), headache with vomiting and nausea (migraine) have been worked out. The trinucleotide disorders in huntington and mutations in the prion protein causing various types of encephalopathies have been established. Present study touches upon some important areas of mental retardation and psychiatry through history, cutting across diverse disciplines and methodologies and attempts recent developments in the field.