IF JACE AND CLARY ARE BROTHER ANE SISTER AND IN Любовь WHAT DO IN THE CITY OF GLASS?

Jace and Clary are not Siblings, but they both have Ангелы blood.

It turns out they aren't related

They ain't siblings.

actually jace isn't jocelyns son, sebastian is, jace is stephen herondale's (the inquisitor's son) son so he and clary end up together :D