If for one reason or another that’s not happening, or just too much or too less, then the biological process is not functioning correctly.

The range that is used to define too much or too little is based on research that starts with an assumption that there is a correct range. While some things like cholesterol have clear consistency with levels and buildup, not everything is that clearly defined.

Keep in mind that homosexuality was scientifically defined as 'not correct' for a long time based on 'biological processes not functioning correctly' because the scientists that defined it that waay assumed that sexuality only exists for procreation. While there is a difference between scientific language and common usage for a lot of things, using terms like correct and normal outside of the scientific context has harmed a lot of people and just saying that is the scientific terminology doesn't help when the scientific terminology was the problem.