It’s okay to treat your children differently.
This is a fact!
As a parent, you would like to be fair, but each child is an individual and should be treated accordingly. And children can usually accept that a parent feels closer to one child than to another. So don’t beat yourself up for feeling that one child is especially cute or smart. Instead, work on how you interact with each child to make sure that one of them isn’t getting the short end of the stick.