How can you have dark hair and snow white skin?

for example i thought hair or skin / colour of the eyes where due to how much melanin is in ur skin [ i know its also genetics] but surely it makes sense to have dark hair and darker skin not dark hair and pail skin, how have you got threse genetics of dark hair and white skin skin? is it possible one of ur anncestors was black with dark hair and then you had another ansestor with blonde pail skin and they mixed together, can you explain this??