According to the word of God, the children are to obey their parents. What level of input the parents give to their children relative to anything is up to the parents, not the children.
"Children, obey your parents in all things: for this is well pleasing unto the Lord." - Colossians 3:20
This would possibly be because the parents appear to believe in the Bible and they desire that their daughters not wear the garments that pertain to men.
"The woman shall not wear that which pertaineth unto a man, neither shall a man put on a woman's garment: for all that do so are abomination unto the LORD thy God." - Deuteronomy 22:5
Even if they are wrong relative to pants on girls (which I know many on this board would believe them to be), it is their decision to make. The father is the head of that house and he will be held accountable unto God for how he ruled his home. Either way, there is nothing abusive or illegal about such a decision.
The head of this house is responsible for all that goes on within it. If he decided that it is a glory for the women to wear long hair and it's a shame for the men to wear anything but short hair, then that's how it should be.
"Doth not even nature itself teach you, that, if a man have long hair, it is a shame unto him?" - 1 Corinthians 11:14
"But if a woman have long hair, it is a glory to her: for her hair is given her for a covering." - 1 Corinthians 11:15
The style of their hair would appear to be a natural style and is how God designed them. Must we be critical because the none of the girls have a beehive, boufant, or a dido flip? And none of the boys have a mohawk or whatever that effeminate cut is called that the emerging church men are wearing?
Their differences should be encouraged so long as they conform to the word of God.