I was pidgeon-toed,and "knock-knee'd" too,which goes with this sometimes,and obviously makes the problem worse.
The Knock Knees are supposed to resolve themselves around the age of 7-8yrs apparently.
My mum was advised by the GP(in the 60's), to buy me Startrite shoes as they have more support than all the other makes around the instep and below the ankle.
My DS had similar problems ,and when he was a year old I took him to see an Orthopaedic Surgeon,who said it would improve when he started walking,and to put him in.....Startrite shoes! ( this being some 30 years later!)
As soon as I was old enough my mum "nagged" me to "turn my toes out",at first I exagerated this and walked like a clown,but it made me aware,and it either corrected itself or I did it,as I'm certainly not pidgeoned toed or knock knee'd now.
My DD1 is also like this and she is 4 yrs old,she wears Startrite and I have started making a game of turning her toes out,and as she trips over sometimes I have told her she wouldn't fall over if she turns her toes out!