Multivariate genetic analysis of ‘environmental’ influences on infant cognitive development

Abstract

A multivariate path model of the relationship between environmental measures and measures of infant cognitive development in 183 adoptive and 165 non‐adoptive families was tested.Environment‐development relationships are not confounded by genetic similarity between parents and their offspring in adoptive families. The structure of the genetic factors that mediate ostensibly environmental influences was assessed by comparing multivariate relationships in adoptive families with those in non‐adoptive families. A maximum likelihood estimation procedure produced a highly satisfactory fit of the model to the data. The results obtained from fitting a series of simplified models to the data indicate that environmental variables measured by the Home Observation for Measurement of the Environment (HOME) have significant influences on Bayley Mental Development Index (MDI) scores, language development as assessed by the Sequenced Inventory of Communication Development (SICD), and a factor from the Bayley Infant Behavior Record (IBR) termed task orientation. However, the relationships of the HOME to the MDI and SICD are mediated to a similar extent by hereditary influences.