I had a professor who did a deep study on the Bush family years ago.
Their daughter died when the kids were all teenagers and George HW was already in politics. Basically Barbara held that family together with both hands. When you figure she raised a President and a governor, gotta figure she did something right.
(Also an interesting note, that same professor was saying that the reason Bush 43 developed his terrible sense of humor was because his dad was always gone, even during that incident, and he took it on himself to always try to cheer Barbara up when she couldn't cope with that death anymore.)
Anyways, RIP