Why do you think parents accord less priority to girls education as compared to boys?
Children be it boy or girl, grow up together in the same environment, but as they grow older girls are made to learn household chores and boys are taught to work outside and earn money. Some parents prefer boy child over girl child; this led to female infanticide.
Women do household works like cooking, tailoring, washing clothes etc. But when the same chores are done by men, they are mostly paid. We must have seen chefs of hotels are male; they even work as a tailor. Hence, it is social norms or stereotypes that anything that is paid could be performed by men.
The parents consider boy as an asset as he would earn in future and would bear the burden of household expenses. Whereas girls are considered a liability because would eventually get married.