Not all sets of parents share an identical parenting style in regards to their offspring. In some pairs, one parent is more thoughtful, one is more caring, one is more present than the other... and in some pairs, one parent is the voice of authority and the other is a lot more doting and easy-going. It's practically a rule of thumb that children require a healthy balance of stern authority and doting attention from their caregivers, but when this trope is in effect, either parent leans a little more towards opposite ends of the balance.