**Core Concept**
Wilm's tumor, also known as nephroblastoma, is a type of kidney cancer that primarily affects children. It is a malignant tumor that arises from the embryonal cells of the kidney. Understanding the characteristics of Wilm's tumor is crucial for diagnosing and treating this disease.

**Why the Correct Answer is Right**
Wilm's tumor is known for its association with certain genetic mutations, such as WT1 gene mutations. It often presents as a large abdominal mass in children, typically below the age of 5 years. The tumor is usually unilateral, but in some cases, it can be bilateral. Wilm's tumor is also known for its response to chemotherapy and radiation therapy, making it a treatable disease.

**Why Each Wrong Option is Incorrect**
**Option A:** Wilm's tumor is not typically associated with a family history of the disease.
**Option B:** Wilm's tumor is not usually a metastatic disease at the time of presentation.
**Option C:** Wilm's tumor is not typically seen in adults.

**Clinical Pearl / High-Yield Fact**
Wilm's tumor is often referred to as "nephroblastoma" due to its origin from embryonal cells of the kidney.

**Correct Answer: C. Wilm's tumor is typically seen in children under the age of 5 years.**