Why is my Sim mean to his wife and kids?

If your Sims have high levels of Free Will they will do whatever they feel like doing. Social Interactions, even mean ones, will increase their Social meters but may damage their relationships with other Sims. Sims seem to choose their interactions with influence from their traits. Evil sims seem to be more prone to mean interactions than Good sims.

There isn't really any rhyme or reason why your Sim had these behaviors. The game is a simulation of human life, but not a perfect one. The next time the father sim interacts with with his family it may be positive or negative. Previous interactions only really affect future reactions if they change the relationship level from friends to enemies. Unless that happened, you cannot accurately predict what your sim will do next.