Burglaries can happen in many different ways. You and your family may have been away from home at the time, maybe someone tricked their way into your house, or perhaps you were busy or asleep when they broke in.
Most burglaries tend to be random rather than planned. Burglars usually choose houses that seem to have little or no security or know that the owners are on holiday or not home. There are certain times of the year where the amount of burglaries goes up, for example at Christmas when burglars know you have more valuables in the home or during summer when people leave windows open to stay cool.