This paper reports on young people's understanding of genes as they near th
e end of their compulsory science education in the UK. A sample of 482 scho
ol students aged 14 - 16, drawn from across the ability range, took part in
this study. Findings, based mainly on written responses to written questio
ns, but supported by interview data, show that this sample had only a very
limited understanding of the most basic ideas relating to function, structu
re, and location of genes. It is argued that these findings are not atypica
l for this population of school students. The implications for teaching the
more complex genetic concepts demanded by the National Curriculum - geneti
c engineering, for example - are considered.