Hi mummies, I am being question by my father why my lo at 4 months can't hold his own bottle while feeding? I don't know that at 4 months I have to start to teach him. How should I start to teach him? dose brand and size of bottle matters?

It's not a MUST to teach. Some babies likes to hold their own bottles, whereas others like to be fed. You can guide the baby hand to hold the bottle while you are feeding, soon they will be able to drink themselves after they got the hang of holding the bottle and feeding themselves.