I'm frequently asked if I know how likely it is to have another child with EA/TEF. The official answer, according to http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1884133/
"The overall risk of oesophageal atresia recurrence in a sibling of an affected child is about 1%."
This refers to having another child from a different pregnancy. In a twin, esophageal atresia is 2 to 3 times more common.