Father's DNA precedes Mother's DNA. If siblings have the same Father they are considered Whole siblings. If siblings have the same Mother but not same Father they are considered Half siblings

It's really debatable as there are so many fields of science and technology. Also national or ethnic bias is also invoked by many making claims to such titles. In short there are many answers. I would suggest typing "List of people considered father or mother of a scientific field" into wikipedia for more info. They have an extensive article there naming nominees.

your mother and your father are considered to be hominoids

If your mother and her brother share the same parents, then her brother's father would be considered your grandfather

They are considered to be a combination of both.