I can't imagine that it would have much impact other than if you feel more attractive/confident one way or the other!

I was born blonde, that white blonde. By highschool it had started to darken though and I would get foils to stay blonde. When my DD was born (I was 21), I just could not be bothered to keep it up so washed through a dark brown and waited to see what would grow out (I was expecting a dark blonde/light brown sort of thing), turns out I'm super brunette naturally now and I love it, I think it really suits me and wonder why I kept up the blonde thing for so long! My fun factor hasn't seemed affected.