Before I returned to my hometown, I had uncovered my father’s secret, which was he had another family.
My older sister, Isabella, was not just "adopted" from an unknown family but actually, she was my father's child from his second family.
After a private investigator followed him for several days, I discovered that the other woman in his life was his first love. She was ten years older than him. Because of the age gap, my grandparents fiercely opposed their relationship. So, my father could not marry the woman he loved and, in the end, he decided to marry my mother.
However, my father had only married my mother to appease his family. Secretly, he never ended his affair with the woman he truly loved. Together, they had a child and she was Isabella.
Both of us were his daughters, but Isabella was born from the woman he loved, which was why he showered her with affection. To legitimize her presence in our family, he lied to my mother. He convinced her that adopting a child would "bring a son into the family."
However, in fact, the reason why my mom did not get pregnant for a long time was because my dad had deliberately stopped it.