There's absolutely nothing wrong, of course, with wanting all your kids in this world to do equally well. In the life of a proud parent, it's just another day. Unfortunately, for one cause or another, in the majority of households, not every child is created equal. Some kids can also struggle with a physical or mental disability, have a problem with drug abuse or something else that is equally difficult.
That being said, the standards for every family member in your household can be changed... even for grown-ups. Other parents are doing this effectively.
It's incredibly important not to equate one child against another when defining your children. It's also necessary not to try to fit them into a mold. On this world, every child is different. No two kids will ever be exactly alike when it comes to stuff like thoughts and accomplishments.
Take the appropriate time to really reflect on each of your kids. Forget about what their friends are doing, forget about what you've read online or on TV, and forget about what your spouse or partner is saying.
Please ask yourself questions like:

In regards to growth, where is my child?

What are my children's achievements?

What is the basic temperament of my child?

What are the needs of my child?

You will start to zero in on your future goals once you have answers to these questions.
Uneven Development Discovery
Each child has a different rate of growth. So, don't panic immediately when you think that one of your kids is a little behind his or her peers. These children catch up gradually in the vast majority of cases. Only a little more time is needed.
You may want to arrange a meeting with each of your child's teachers at this stage. Ask if you can do something to support your child with any delays that he or she might be experiencing.
Adjustment to separate stages
Assessing the "reasonable behavior" of each of your kids often means taking into account his or her abilities. For example, you might want to drive to your next vacation destination instead of flying if one of your kids happens to be afraid of heights. Don't just expect the kid to get on an airplane immediately and tolerate a long flight with no problems at all.
When changing the expectations of family members, always be respectful of the opinions of other people. It's not rare for the other parent or adult of your child to doubt your expectations.
Sit down with the person if you disagree, and ask them why they feel the way they do. Many times in cases like these, coming to an understanding is simpler than you think.
Is it time to change your expectations for your family members upon reading this? There isn't a better time to get started, if so. Usually, the adjustment takes some time, so do not expect it to happen overnight. But, with extra diligence, before you know it, you can accomplish the task.