Why are my eyes different color than my parents' eyes? It's not dominant nor recessive?

Genetics mostly. Eye color primarily determined by genes from your parents. Blue eye color for instance requires one recessive blue gene from each parent. Brown iris gene is dominant over blue so if child gets blue gene from mom and brown gene from dad then child will have light brown iris rather than blue. Certain diseases, eye trauma, and medications may alter eye color from original eye color after birth.