Well, I was born a bleach blond as well SD. My hair although called dirty blond, I appear brownish. When I am outside alot during the summer or when Im in Africa, my hair REALLY lightens up. Im sure you are the same.
My dad actually was the same as me. When he was young, straw blond. When he was about my age now, he went brownish, and it got lighter the more he was outside. thirties and he was a real dark brown almost black, hes now grey lol. I like to bother him about it.
It seems to be an eastern european thing.