Historically, women have been the caretakers in a family. Decades ago, courts would assume that placing the children with the mother was the best thing to do. But attitudes have changed.
Texas law assumes in every case the best thing for the children is to have both parents equally involved in their lives.
The idea behind child custody has always been to do what is best for the children. That has not changed. What is different now is there has been more study into what really is good for kids. And research has shown over and over that children do better when they have both parents in their lives.
The evidence is that kids need a chance to develop a relationship with mom and dad. They need time with each parent to do so. Because of this, courts have changed how they approach custody cases and made the whole process fairer for fathers, who used to get the short end of the stick.
There are always exceptions. In some cases, one parent is the better choice due to issues with the other parent. For example, a father with substance abuse issues or who has a history of violence may not create the best environment for the children. The court will consider all factors when making decisions.
In addition, if a father has been largely absent or hands-off with raising the kids, then he probably will not get the best custody arrangement. The court does not want to pull the children away from the parent who has provided all the care so that the custody deal may favor the mother.
The bottom line is courts do not approach child custody cases anymore thinking the mother should have primary custody. The court will consider all factors and try to award equal time to both parents.