What are the causes of congenital heart disease?

Multiple: Congenital heart defects are a collection of issues that could be devastating early or of almost no consequence even in the long. As there are a variety of maladies, the causes are multiple as well. Environmental factors, genetic abnormalities in either of the parents and a combination of these factors lead to congenital heart defects.

??????: The most common cause is that we have no direct cause for congenital heart defects. They can be associated with certain genetic conditions such as down's syndrome. I also think in my distant memory that there are some that can be drug/chemically induced.