Despite a substantial body of research suggesting genetic influence on educationally relevant behavioural traits, it is not clear how the nature-nurture question is perceived by teachers. In order to answer this question, we surveyed 667 UK primary school teachers, and for comparison also surveyed 1,340 parents about their perceptions of genetic and environmental influence on personality, intelligence, behaviour problems, learning difficulties, and mental illness. For these five domains of behaviour, the percentages of teachers who reported that genetics were at least as important as environment were .87, .94, .43, .94, and .91, respectively. Results for parents were similar (.92, .93, .54, .86, and .89). We also found that 80% of teachers reported no coverage of genetics during teacher training.