Although there is some debate about the exact proportions of each most psychiatrists now accept that the nature/nurture debate is a pointless one and that mental-health problems are due to a complex interaction between people's genes and their environment. ADHD is no exception to this and a team of researchers from Michigan State University studied 304 youths to look further into the causes of the condition. They looked at variations in a genetic region - 5HTTLPR - which led to either a very low or very high production of serotonin in the brain and the children's tendencies to blame themselves for arguments between their parents. They found that the children with variations in the gene and who were more prone to self-blame had more ADHD symptoms.
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