I know there was a problem with mermaids, but that was apparently fixed in a patch, now since installing Magic, my 2 x spellcasters (Maybe I should have posted in the pack forum, but just in case it i...
The game's genetic engine is trying to give the child the hair colour of the silver haired parent. It is by design, since toddlers and children don't have grey (or the other unnatural colours such as blue or pink) as an option, that they end up with a random hair colour.