Sugars were full-blown and the sugar came in heavily in the late 1800s, and it was considered classy, panache to have candy in your home because you had to be rich to afford candy. So, people would eat candy and think, oh, I am so terrific. What they were doing was poisoning themselves faster than anybody else.
That's why the rich children were always more unhealthy. They had more eye problems, they had more physical problems. They were weaker punier because they got all this medical attention, and they got all this bad food. It was elitist.
Let me tell you there's lots of dogs and cats out there and other animals who interbreed all the time and don't have those problems.