There is definitely strife caused by preferring one child over another. Parents must strive to keep all signs of favoritism out of their relationships with their children.
Another problem created by parents is caused by gender. One parent hoped for a son, but had all girls instead and felt disappointed. If allowed to continue, this can damage the parent/child relationship.
So, count your blessings, not your what ifs and enjoy the children God has blessed you with - each and every one!
“Lo, children are an heritage of the LORD: and the fruit of the womb is his reward. As arrows are in the hand of a mighty man; so are children of the youth. Happy is the man that hath his quiver full of them: they shall not be ashamed, but they shall speak with the enemies in the gate.”