Board Thread:Speculation House/@comment-14138255-20151129182644/@comment-25396609-20151129191846

If the semblance is parasitic as I mentioned (although more a symbiotic parasite) it is possible that it is not so much inherited as it latches onto their soul at birth and prevents them from developing a different semblance (technically beneficial but has pretty terrifying implications).

Anyhow, here's the thing Vedran did to try and understand the spell circle vs glyph difference.