Sally and mark are brother and sister from the same parents. sally has blonde hair and green eyes. mark has dirty-blonde frizzy hair and hazel eyes. why is this? !

This is because of genetics i made a chart below and added discription below that.

Father            Mother

blonde            dirty blonde                   Hair Color

hazel               green                             Eye Color

curly               straight                            Hair Type

In the rules of genes the child gets half of the mothers side and half of the fathers side so if the mother is short and the father is tall and we add these up there could be several different variations but to what Mark and Sally got Sally got more of her mothers side in my thought and Mark got more of his fathers side. But this could be different since we are not informed what the parents look like.

Hope this helps and have a great day!

PLEASE mark me brainliest.

your answer is "the 1950's"