This e-book focuses on the topic of genetic influences as they relate to the challenges experienced by people who have intellectual/learning disabilities, and how these may be best addressed and helped. Two main themes are presented relating to genetics as it applies to people who have intellectual disability and associated mental health challenges, namely the ever-growing field of behavioural phenotype research and clinical practice, and the frequently experienced developmental neuropsychiatric disability known to have strong genetic underpinnings, namely attention deficit hyperactivity disorder (ADHD).