Abstract
Background: Characteristics of parent-child interaction (PCI) early in life have been
associated with later development in the child. Twin studies can help to disentangle child
contributions to parent-child interaction, e.g., by assessing the influence of the child’s genetics
on his/her social environment, which includes parental behaviour.
Methods: Infant twins from a community sample (354 monozygotic (MZ), 268 same-sex
dizygotic (DZ)) were assessed in terms of PCI at age 5 months. We used the classical twin
design to map the aetiology of several parent and child PCI scales and their covariation. We
investigated the relations between PCI and later parent-rated child’s social communication,
language, and autistic traits at ages 2 and 3 years.
Results: Heritability was below 20% for all the included PCI traits. Unique (nonshared)
environmental influences substantially overlapped across several PCI scales, suggesting that
idiosyncrasies linked to each session shaped the scoring of several traits in a systematic way.
Factor analysis revealed three uncorrelated latent factors, which were conceptualized as ‘child
negative affect’, ‘positive affective interaction’, and ‘parent’s supportive strategies’. Parents
who were rated highly on ‘sensitive responsiveness’ at 5 months tended to rate their offspring
higher in terms of socio-communicative and language development and lower in terms of
autistic traits in the second and third year of life.
Conclusions: This study maps the phenotypic and aetiological structure of PCI in early infancy
and supports the view that parents’ sensitive responsiveness towards their infant is associated
with later developmental gains in several domains. We did not find strong evidence of any socalled evocative genetic effects on parent’s behaviour. We discuss the results considering the eral challenge for lab-based observational PCI measures to capture the richness of parentchild interaction.