Faecal Microbiota Analysis in Neurotypical and Autism Syndrome Disorder Siblings

Inclusion Criteria: * Children of both sexes who are diagnosed with ASD and under the care of ESNEFT who have a neurotypical sibling (either full or half sibling), who share their living environment. This is due to the study requiring stool samples that are from siblings, to control for genes and environment where possible. * Aged 3 years to 10 years old (at time of consent) * Parent/guardian able to consent to participate * Parent/guardian able to complete required surveys (or with accommodated adjustments) Exclusion Criteria: * Use of antibiotics in the previous 4 weeks * Not under the care of ESNEFT * Children \<3 years old and \>10 years old * Children that don't have half or full siblings * Parent/guardian unable to provide informed consent or complete surveys, despite reasonable adjustments being implemented