A stepchild is someone who becomes your child through marriage rather than birth. When your parent marries someone who already has children, those children become your stepbrothers or stepsisters, and you become their stepsibling. From your new stepparent's perspective, you are their stepchild.

The relationship can feel strange at first. You might suddenly have a stepbrother who takes up space in what used to be the guest room, or a stepsister who now sits at your dinner table every night. These new family members didn't grow up with you, so you don't share all those early memories that biological siblings have.

Today, stepfamilies usually form after divorce or when unmarried parents find new partners.

Sometimes people use the word stepchild figuratively to describe something that gets ignored or treated as less important, like saying the school's art program became the stepchild of the budget when funding got cut. This usage reflects an old, unfair stereotype that stepchildren were treated worse than biological children, a notion that matters far less today, since stepparents and stepchildren can form deep, loving bonds.