The researchers factored in whether the child had the short or long form of the serotonin transporter gene, involved in nerve signalling and which other studies have linked to anxiety and depression. File photo
Research by international experts, including a Stellenbosch University academic, has found that toddlers with a particular genetic characteristic benefit more from interventions than others.

A study led by Professor Mark Tomlinson of the Psychology Department at Stellenbosch University has now revealed a large, hidden role that a child's genetic make-up can play in intervention efforts to maximise his or her development.

In the original study an intervention was implemented between 1999 and 2003 in which expectant mothers received a home-visit parenting intervention to improve attachment with their children.

Attachment was used as a measure of a child's psychological security and is predictive of future well-being. In that study Tomlinson, together with colleagues from the University of Reading, UCT and the Parent Centre, found the intervention had a small-to-moderate effect on mother-child attachment, which was evaluated once the child reached 18 months of age.

The follow-up study, conducted nine years later, re-examined the original attachment results and revealed that the intervention had, in fact, worked well for toddlers who had a particular genetic characteristic, Tomlinson said.

In the follow-up study, caregivers and their children were re-enrolled and the original attachment results were reanalysed based on whether the child had the short or long form of a gene called SLC6A4.

The researchers factored in whether the child had the short or long form of the serotonin transporter gene, involved in nerve signalling and which other studies have linked to anxiety and depression.

Children with the short form of the gene, and whose pregnant mothers received the intervention, were almost four times more likely to be securely attached to their mothers at 18 months old (84%) than children carrying the short form whose mothers did not receive home visits (58%).