When I was 5 I was with my cousin(girl) she loved playing with Barbie and silly me asked if I can play Barbie with her she say yes and my brother caught me brushing her hair
What's wrong with boys playing with dolls??? The only way that you feel that it's inappropriate is because those around you acted inappropriately to you playing with dolls.
When I was 4 and 5 i played barbie with my little sister. She was a year younger and we were very close. It's one of precious few memories i have of her.