I'm an occult player, and i've been using the husband1 spellcaster to wreck havoc everywhere, and ofcourse i tried out the duplicato spell. I believe it's the reason why my married sims (with three kids) have become brothers. Tried all suggested fixes, worked for 5 min, then reverts back to being brothers. Sucks.
The only thing that worked for me, won't be a solution that is ok for most people.
I "played with genetics" made a twin of the wife, then deleted the wife.
made the "twin" a wife of the husband.
so she looks the same but obviously is like a new sim. *cries*
