Rotation of hips similar to slice causing an in to out swing plane. The club face is square but your hips are rotating to the right so you will push the ball to the right. If the hips can't turn due to poor posture you will turn the hips too late in the downswing causing a hook or slice. Your hips and shoulders will not turn together so you will not be square at impact. You will also tend to compensate by either closing or opening the club face too much.

The diagram, (above right), shows the typical pushing posture with the centre of balance indicated by the red line. The faded image of a golfer dressed in blue is the correct posture. The correct posture should have a spine angle of 30 degrees, or as demonstrated in the diagram, at 11 o'clock or 1 o'clock depending if you are right or left handed.