Orofacial clefts, which include cleft lip and/or palate are amongst the most common birth defects in humans and pose a large psychological and economic burden on affected children and their families. The majority of cases are non-syndromic and are the result of a complex interplay between environmental influences and genetic factors. Because the defects occur during early embryonic development, maternal factors, such as smoking and alcohol consumption, folate deficiency and hypothyroidism, acting both before and during pregnancy have been suggested as risk factors in epidemiological studies. However, maternal behaviours during pregnancy are strongly socially patterned and this could mean that genetic risk factors for cleft are also associated with educational and socioeconomic factors. We have previously found that genetic risk factors for childhood psychiatric disorders, when considered en masse as a polygenic risk score, are associated with social factors and maternal behaviours in the general population.