it has to do with recessive genes. My niece has blond hair and blue eyes. Her mother (my sister) has dark brown eyes and my ex brother in law has dark brown eyes as well. all her grandparents except for one has brown eyes and one grandpa has blue eyes and blond hair (basque). So it has to do with genetics
The Herobrine character does not exist on Minecraft. The stories about Herobrine are imaginary with an intention of misleading people, so that the users can play mods which have been installed into their games without their knowledge.