Molecular genetics is an area that is currently progressing rapidly. It is now clear that almost every aspect of human behavioural development is genetically influenced, and the hunt is on to find, replicate and understand the function of the relevant genes. However, although most child psychology and psychiatry professionals recognise the role of genetic influences on the traits and disorders they work with, the field is one entrenched in language and indeed statistics of its own. This makes it a particularly hard area for those not working in it to dip into. Furthermore, it may not always be obvious how the findings of molecular genetics are relevant to other areas of research and to practitioners. For this reason, we decided the time was right to bring together a series of papers using current methodologies to examine genetic influence on aspects of child psychology and psychiatry, and to attempt to show in each how these findings are relevant to the broader field.

The commentary by Robert Plomin provides an authoritative overview of where the field currently stands, including a summary of the papers in the section, and describes exciting developments that should help pave the way in the future. This is followed by two introductory guides covering the language and statistics of molecular genetics. The seven empirical papers cover a wide range of phenotypes, including ADHD, reading disability, speech and language disorder, genetic cognitive ability and Prader-Willi syndrome. The methods used also range considerably, reflecting the variety of approaches available. Some are as simple as a case–control design, making it easier to see how this type of information may in future be incorporated into ongoing non-genetic studies.

The four remaining papers in this issue include one on learning disabilities, one on visual attention in deaf and hearing infants, one on self-perception of psychiatric problems, and one on a Chinese version of a diagnostic interview. The study by Eisenmajer and colleagues examines the important question of overlap between specific language impairment and specific reading difficulties. The study identified three groups of children, those with just one or other of these problems, and those with both. The latter group performed more poorly in general on both academic and phonological processing tasks, raising the possibility that this should be considered as a distinct third group.

The study by Harris and Chasin highlights the importance of engaging the attention of deaf children through differing means to those used in hearing children. Deaf mothers of deaf children were most adept at using a wide variety of techniques to attract their child's attention. The findings suggest that hearing mothers of deaf children may benefit from support early on to help them assist their children develop good communication skills.

Sourander and colleagues examined the links between early self-, parent- and teacher-reported emotional and behavioural symptoms and subsequent recognition of psychiatric problems and psychiatric diagnoses 10 years later in a sample of Finnish males. Of those with psychiatric problems, almost three-quarters recognised that they had either mild, definite or severe problems. However, only a minority were recognised by the health services as having a psychiatric disorder. The strongest predictor of psychiatric disorder was parent- and teacher-reported perceived need for treatment at age 8 years, suggesting that early school-based screening could be useful.

Despite the huge youth population in China, little is known about psychiatric morbidity in this community. One obstacle to progress in this area has been the lack of validated psychiatric instruments. The study by Ho and others sets out to address this need by examining test–retest reliability of a Chinese version of the DISC-IV, producing findings similar to those from the original English version.

I hope that you will enjoy this issue and that the special section on molecular genetics will prove both informative and engaging!