I'm 25 and have trouble with my legs. i can sit in what they call the 'w' position without pain. what could it be because of?

Hip problem?: Needs examination by a doctor licensed in your area but generally speaking there are a variety of ligaments/muscles around the hip area that might be playing up and can make hip movements unusual. A physical examination may be useful and if remains unclear the doctor would then be able to consider tests such as X-rays and possibly scans/ to clarify (depending on what is available locally)

Anteversion: There is a variation in angulation of the hip joint, which is normally pointed about 10-15 degrees anteriorly. When it is pointed forward more than that it is called femoral Anteversion. People with this tend to walk with their feet turned inward and can easily internally rotate their hip. Thus they are very comfortable sitting in the "w position".

As a child-: -sitting in this position influences the direction of growth leading to femoral ante version. When you walk this causes you to looking knocked kneed. To late to do anything now without a surgical procedure.. some call it squinting patellas .