I have always been fascinated with twins. I have twin grandsons who are two-years-old. They are awesome together, but the two are not similar in personalty only in looks.
One is serious and gentle; the other is a clown and rough. One day the rougher one hit his brother who just sat there and took it. So I scolded the hitter, which made the gentle baby laugh. This encouraged the rougher one to hit his brother again who laughed again.
They just compliment each other in play and personality. The "naught" seems to entertain the gentler one, and that's how they get along. I often think the quiet one is telling the other guy what to do. He seems like the mastermind in their antics.
My poor daughter has such a time keeping up with them. They have separate beds, but we often find them cuddled up together and hugging. I have nine grandchildren and dearly love them all, but the twins are so special, tiring, but special.