Anyone with "dominant" traits (dark hair, eyes, etc.), CAN have a masked recessive gene, which is how a recessive person (blonde hair, blue eyes) and a dominant person can have a recessive child. Also, not all recessive genes line up, example: having one parent's dark hair (dominant) and the other parent's light eyes (recessive). I know it's a bit basic, but good ol' Punnett squares explain all of this.