http://www.egscomics.com/d/20020527.html
Mr. Verres may be good at convincing people the truth ain't out there, but he sure does a lousy job of dealing with teenagers. Really, he knows his son. Why in the world did he think it would be a good idea to mention that? Maybe he assumed that Tedd would think that as Grace isn't actually human there wasn't any chance of something like pregnancy if they had sex, and Mr. Verres was trying to specifically point out that such a thing was not the case but chose his words poorly. After that I can only assume his instincts as an endless barrel of exposition took over.