S ome genetic traits can bring on the warm fuzzies, conjure up memories of relatives no longer with us and inspire pride. "He has his grandfather's chin," someone might say of a newborn, or "that kid got her mother's brains." Other traits-say, a genetic mutation that could lead to cancer-are decidedly less welcome. Mapping our family's medical history can help us identify diseases earlier or figure out what preventive measures might be necessary to stop them from developing at all. It's the reason your doctor asks you to outline whether your mother was diagnosed with breast cancer or your father had heart disease. 24 W IN TER 2019