Depends on variables. Most cases of complex congenital heart disease happen in a sporadic manner. The general risk of a parent with a chd having a child in these sporadic forms is about 6%.This is not specific to the same defect but includes all defects.When it is part of an autosomal disorder or chromosome deletion syndrome, the risks are higher.
In some families. In some families, there are genetic factors that affect the development of various conotruncal heart defects, which includes tetralogy of fallot. One gene defect that can result in tof is 22q deletion. There is variability in both penetrance (does the disease show up) and expression (the exact way a disease occurs.).