My Son Walks On His Tip Toes All The Time. What Could Cause This?

My sister was doing the same thing staying on her tip toe we took her to a foot doctor who told us that the ligaments in her leg coming from the the heal to her leg weren't streching as she was growing which is why she walked on her toes they did surgery she was in a wheel chair for a couple of weeks so they could stretch them themselves she does have scaring but she walks fine now.Sorry my spelling stinks

You do not say how old he is - but I can tell you that babies/toddlers often do this when they first start walking. When he is relaxed and sleepy just gently bend his ankle so that his foot is how it would be if he were standing correctly. If you can do this easily then there is every chance he will just start to do it naturally, in his own time.
If it is difficult and stiff then you need to see a podiatrist or doctor. As you also do if he has been walking like this for say, 4 months or more.

Just wanted to let you know just like Harka mentioned my son did
tip toe walking,or should I say running as well..So did my brother
as my mom told me when I was worried.This is most likely the stage he is going through and you should not worry.And yes if its been a long time and this is the only way he walks I would check with the
pediatric podiatrist or orthopaedic specialist.