Final answer:
The etiology of congenital heart defects is a combination of genetic and environmental factors, with genetics setting the predisposition and environmental factors contributing to their manifestation.
Step-by-step explanation:
The etiology of congenital heart defects is a combination of genetic and environmental factors. While genetics provide the underlying predisposition to heart defects, environmental factors such as maternal health, infection, and exposure to toxicants can contribute to the manifestation of these defects. Lifestyle choices, although not directly mentioned as a cause for congenital heart defects, can influence cardiovascular health more broadly, impacting metabolic syndrome and increasing the risk for cardiovascular diseases.