No one wanted us that is why my brother and I went from one foster home to another. The longest we stayed in a place was three months, and then we would be transferred again. Couples were often excited to see us at first but then eventually give us up.
It is hard to be a parent, especially if you got more children to manage. There is no one formula that fits in raising all of them in one household.
We, parents, are humans, too, and we are also bound to make mistakes. We may even sometimes end up discriminating against one of our children because of many reasons such as frustrations regarding attitude and/or school performance.