In a study, researchers found that a sex chromosome trisomy (SCT) occurs when a child is born with an additional X or Y chromosome (47,XXX; 47,XXY; or 47,XYY). To identify signs for support and therapy, this international cross-sectional study looked into how children with SCT perceive faces and how this affects face recognition during early life. This study included a population-based sample of 98 children without SCT (Mage= 3.7) and a group of 101 children with SCT (ages 1-7 years; Mage= 3.7). Using an eye-tracking technique that measures first fixations, fixation durations on eyes of static faces, and fixation durations on eyes and faces in a dynamic paradigm, eye gaze patterns to faces were measured (with 2 conditions: single face and multiple faces). The neuropsychological test battery NEPSY-II Affect Recognition was used to gauge affect recognition. Both the Netherlands and the United States were used for recruitment and evaluation. According to eye tracking data, children with SCT have shorter proportional fixation durations on faces starting at age 3 compared to children without SCT. Additionally, there were deficits in the clinical range for recognizing effects (32.2% of the SCT group scored in the extremely low range). These findings emphasized the need for more longitudinal research on the development of social cognitive abilities in children with SCT, for monitoring affect recognition abilities and implementation (preventive) interventions meant to promote the growth of attention to socially significant information and affect recognition.