Similarly, I would definitely not have been born if the Nazis had not taken power in Germany and subsequently annexed Austria, as the latter event led my grandfather to flee to the Netherlands and, later on, to meet my grandmother. This isn't something "positive" about Nazism or the Anschluß, though, and it would be in extraordinarily poor taste to formulate it as such.
To take this even farther....in all likelihood, virtually no one currently on Earth who was born in the 1940s or later would have existed if the Nazis hadn't come to power, simply because the lives of everyone around at that time would have unfolded rather differently, and so many people would have married different partners and had different children. (I guess this doesn't necessarily apply to neutral countries in far flung reaches of the globe, but close enough.).
One idea for a sci-fi story I had was what if someone had a time machine and went back in time a few centuries, and didn't do anything particularly remarkable while there, but just because of the butterfly effect from the interactions that the protagonist had while in the past, when he/she returns to the present, everyone they knew is gone, and replaced by a different set of people resulting from the new timeline. The world as a whole is largely the same, but the individual people in it are all different. Some sci-fi author has probably already written a story like that, but I'm not aware of it.
