If you do a makeover or Simsurgery on a townie or NPC, say changing their hairstyle or color, and then move them in, what will their genetics be? Will they be the same as if you hadn't done anything to to them, or will they be set to the new values once they become playable?
If you do it in-game, it doesn't change genetics. If you do it in SimPE, it does -- that's the main reason to use SimPE in the first place, since most cosmetic changes can already be done in the game.