Clary unintentional, as Valentine didn't know Jocelyn was pregnant when he experimented on her with angel's blood.
Jace intentionally as the angel's blood that Valentine used to experiment on him with gave him certain characteristics (such as the ability to jump supernaturally high).
I'm not familiar with the books, but if this has anything to do with the trope beyond being about angels, it could do with a rewrite to make it clearer. It could also do with a rewrite to not be completely spoilered out.
I pulled this:
I'm not familiar with the books, but if this has anything to do with the trope beyond being about angels, it could do with a rewrite to make it clearer. It could also do with a rewrite to not be completely spoilered out.