) 

 Edit from UK man: I was very blond as a boy, up to the age of about 5, when my hair turned progressively darker, eventually (10ish?) ending up fairly dark brown.  My first daughter (whose mother had very dark brown, almost black, hair) was also very blonde before school age, but by 10ish had hair slightly lighter than mine (which colour it has remained).  My second daughter (different mother, but also with dark brown hair), had very blonde hair as a small child, and, although it has got darker, her hair is still blonde at 9 (when exposed to strong sun, it turns very blonde, almost white). 

 So, this certainly does happen.  Because of mine and my daughters' experiences, I've often talked to people about this, and I am frequently told that brown haired people were blond as children, or they have had children who were blond(e) and then turned brown. 

 (My apologies for not signing this, but I don't know how to do it.