While earlier studies suggested potentially lower oxytocin and vasopressin levels in the plasma of children with ASD as compared to typical children (Modahl et al., 1998; Al-Ayadhi, 2005), subsequent research has shown that plasma oxytocin levels tend to be similar within members of the same family, irrespective of a diagnosis of autism, although do correlate with social communication abilities overall (Parker et al., 2014). This evidence concerns the gene OXT and autism.