Do you think M. Rasmodius / The Wizard is Abigail's father? We all but KNOW Caroline fucked Rasmodius, hell this might be part of why he's divorced.

Personally I believe the Chestnut color hair thing (about Abigail used to have that) is either (if you look in the first description of abigail ever) that the Chestnut color hair Abigail originally had comes from Caroline's Side of the family OR... my personal opinion possibly like some weird magic sex thing where Pierre's genes are in there too. This is further supported by the fact in some married dialogue Abigail hasn't dyed her hair (purple) in a long ass time it just STAYS this way. Either it turned purple some time later (permanently)

ALTERNATIVELY maybe Caroline was dying Abigail's hair chestnut? Can you do that secretly?