Background/Objectives: Autism Spectrum Disorders (ASD), attention deficit hyperactivity disorder (ADHD), and Tourette Syndrome (TS) are neurodevelopmental disorders (NDD) with overlapping symptoms suggesting a partially shared genetic factor. This study investigates the prevalence of connective tissue-related conditions in individuals with ASD, ADHD, or TS. Methods: A questionnaire was administered to families of 120 individuals with ASD, ADHD, or TS, collecting sociodemographic data and examining 10 types of disorders affecting various organs and systems. Statistical analyses were performed using STATA 16.0, with a significance level set at 5%. Results: Among the 120 cases, 48 had ASD, 36 had ADHD, and 36 had TS. Flat feet were significantly more common in individuals with ASD (52.1%; OR 7.20; p<0.001), ADHD (52.8%; OR 6.73; p=0.001), and TS (38.9%; OR 3.70; p=0.034) compared to controls (13.6%). Hypersensitivity was more frequent in individuals with ASD (56.3%; OR 5.90; p=0.001), ADHD (50.0%; OR 4.11; p=0.011), and TS (58.3%; OR 5.35; p=0.003) compared to controls (18.2%). Myopia and ptosis were more common in ADHD (30.6%). There was a possible trend towards orthodontic device use in TS (OR 3.20; p=0.076). Flat feet and hypersensitivity were also common in fathers (31.0% and 36.4%, respectively), mothers (31.0% and 15.2%), and patients (43.8% and 55%). Conclusions: These results suggest common aetiopathogenetic factors, with connective tissue anomalies potentially underlying different clinical phenotypes. Further studies are warranted.