We're treated to a glimpse of Emma's sister as wife, daughter, mother and sister. Isabella seems to juggle everything amazingly well, and it's obvious she dotes on her husband and kids. I have a feeling that when she isn't at Hartfield and in her father's immediate presence, she may be a little less nervous.
She certainly does have a lot of her father's traits. I wonder how much that has to do with the death of Mrs. Woodhouse. Emma doesn't remember her mother very much, but Isabella certainly would, and the memory of her mother's death, especially if she died following any kind of lingering illness, may have been enough to make Mr. Woodhouse overprotective of his own health and his daughters'. Emma was young enough for Miss Taylor to influence her outlook, but Isabella may already have absorbed her father's fears by the time she arrived on the scene.