> The real comparison would be between SSRI-treated patients and untreated depressed patients, because healthy people aren't prescribed SSRIs.

I see it very differently, as you are focusing entirely on the parents and completely ignoring the children. If the untreated patients weren't going to have kids, the question is only whether or not the children are happy. If the children of parents with antidepressants are more likely to require antidepressants themselves, I'd say that's indicative of a serious problem.