## 1 Introduction  
In the sports domain, birth dates are frequently used to classify young athletes into different categories. Previous studies have indicated that young athletes born near the selection cut-off date (i.e., the oldest in their group) and those born far from this date (i.e., the youngest) may exhibit significant differences in their physical and psychological development [1]. This distribution bias results from the age groups established by sports organizations, which typically group young athletes into categories spanning two consecutive birth years. Although this approach aims to balance competition among athletes, it causes notable differences in relative age: two children competing in the same category may differ by up to 23 months if they are born in different years, while those born in the same year can show a variation of up to 11 months in age [2]. This generates an advantage for athletes born close to the cut-off date in terms of sports performance compared to younger athletes [1]. As a result, during assessments conducted by sports organizations, the former are more easily identified as talented or promising compared to their later-born peers [3]. This increases their chances of being selected by coaches and scouts [4, 5, 6]. Consequently,there is a disproportionate representation of athletes born near the selection date. This phenomenon is known as the relative age effect (RAE) [7; 8]. Various mechanisms triggering the RAE have been explored in numerous studies, with the \"maturation-selection\" hypothesis being the most widely accepted explanation for its existence [9]. This is due to the delay in the physical, cognitive, and emotional development of children born later within the same competitive year [1]. However, according to [PERSON] et al. [10], physical maturity should not automatically be equated with talent, as social agents often falsely associate physical maturity with actual skill differences, thereby accelerating the RAE through this misconception. These authors propose that parents influenced by the [PERSON] effect, coaches through the Pygmalion effect, and athletes through the Galatea effect. Therefore, the interaction of these three effects helps to understand how the RAE can have a lasting and significant impact on sports performance and success [10]. A child born in the early months of the year may be perceived as more talented due to their greater physical maturity at the time of comparison. Coaches' expectations may be higher for this athlete (Pygmalion effect), leading the athlete to develop greater confidence and belief in their abilities (Galatea effect). As the athlete receives more training and opportunities, their initial advantage is amplified ([PERSON] effect), perpetuating their success and reinforcing the perception of their talent. According to the heuristic model of development systems based on constraints proposed by [PERSON] et al. [11], the RAE is multifactorial and cannot be understood as an isolated phenomenon but rather as the result of a complex system of interactions among three types of constraints (individual, environmental, and sport-specific), highlighting the need for interventions adapted to the multiple levels affecting athlete development. Thus, the RAE can impact the developmental capacity of later-born athletes, potentially leading them to abandon their sport altogether [8; 12; 13; 14], resulting in a significant loss of talent. Given the pressure to achieve short-term results, players with earlier birth dates often have a higher likelihood of being selected, leading to more incentives and real opportunities [9], while the opposite is true for later-born athletes. In addition to the RAE, recent research has also emphasized the influence of birth order on an athlete's likelihood of success. A study by [PERSON] et al. [15] specifically examined how both birth month and birth order affect the probability of becoming a professional football player.