Shinra has a funny way of acting towards his kids. Maybe he did know & treated Lazard something like Rufus. Whether that's an "I'm terrible at showing affection" or "come & get me, if you can," I have no fucking clue.
Gast was the head of the science department, but that doesn't really mean he did anything. I mean, let's face it, executives tend to do quite a bit of sitting on their asses & ordering around underlings. From what we see, Hojo & Hollander do all of the work. They even end up being held responsible for the success or failure of their projects.
Another way to think about it is that, if Sephiroth is about 30 years old & Aerith is 22 years old, then for nearly 2 decades, Hojo was responsible for all of the scientific work that went on, & we know that a lot of advancements in SOLDIER & other areas took place. He was especially competent in bio-engineering, even to the point where he had a machine that could fuse things on the genetic level.
I can't really point to anything for sure & say, "He invented it," but he did seem to know his shit. I can't point to a single experiment of his that really didn't acheive a desired result.
In response to his shortsightedness, I would argue that, like any good mad scientist, Hojo always saved some of his experiments to power up himself, when he needed it.
