Provided all the joints work as they do in real life, a marionette cannot help having natural posture and movements.
The first question that always needs to be answered is the location of the centre of gravity within the body
In the case of clothed figures, it is of only minor importance what the joints look like. Visible joints, however, are a challenge for the marionette maker. In every movement and every posture which the marionette is able to adopt, the two segments that meet at the joint should form a smooth match, both physically and visually.