Mother-in-law's strange behavior towards her eldest grandson

Basically, the first one is biased, because the first one is to feel with heart and raise with heart. Both the second and the third are experienced. According to the rules, the first one can be raised well. But it doesn't have to be so hard. Because it is the first experience with your own heart. Don't worry, there must be a reason for the second and third partiality, which is caused by not being smart enough and liking it too much. I still don't know how to suit his grandmother's appetite. The first child, he knows how to please grandma.