User blog comment:B214/Question and Answers 6/@comment-217.115.65.21-20190327194458/@comment-73.160.58.215-20190401203827

The whole reason why they are called "miracle children" in the first place is due to the difficulty in successfully conceiving one, the slightest mistake of either parent would result in a half-fallen instead (and likely the angelic parent's fall as well). There is every reason to believe that they are capable of falling as well. The biggest question is whether their human blood makes them fall even more easily than pureblood angels, or if it instead gives them a certain degree of resistance to falling. In my personal opinion, the latter is more likely, and it potentially explains why Teodoro hasn't fallen due to his hatred of Devils.