This study investigated the relationship among gender, sibling constellation, age, and young children's creativity performance in the Fluency, Imagination, Originality dimensions of creativity, as well as the developmental trajectory of their creativity performance. In total, 493 young children took the Torrance's Thinking Creatively in Action and Movement tests (TCAM), Chinese version -- Taiwan. Statistical results of independent samples t-tests and correlational analyses showed that amongst gender, sibling constellation, and age, the predictive power on the three dimensions of creativity in TCAM all increased with age, regardless of gender and sibling constellation. More specifically, across age, boys performed better than girls in all three dimensions while children without siblings were more creative than those with siblings in Fluency and Originality, but not in Imagination. Regression analyses results confirmed that taking gender and sibling constellation into consideration, the developmental trajectory of these age 4 to 8 children had an overall upward trend in all three dimensions; yet, there was a period of stagnation and even a gentle decrement for boys' and girls' Originality between age 5 and 7. Possible social and environmental factors such as curriculum and pedagogy changes these children experienced during ages 5 to 7 were discussed.