Estimating A Child's Haircolor

Just curious, since my grandmother predicted I'd have red haired children (she's 'psychic' ;) ). Anyone who knows this kind of thing want to provide an estimation of how likely that is?

My father has dark red hair and my mother has brown, and mine is golden blonde and my beard is a mixture of red and blonde. My great-grandmother on my mother's side had red hair as did all of her siblings.

My girlfriend's parents are both blonde (father ashen, mother golden) and the paternal grandfather is ash blonde with several redhaired sisters while the paternal grandmother has light brown hair (one of her sisters is very light blonde and the other black-haired). The maternal grandfather has brown hair and the maternal grandmother has red hair. My girlfriend was born with strawberry blonde hair but it is now ash blonde.

Thanks :wink