I need clarification about metal gear solid 1 story setup. I need help from an expert.

i've already tried to ask here but i really didn't get an answer to my previous question, i'm not native speaker and the games doesn't include my language at all. please explain to non english speaker as me the following if you know the answers:

1. why in that briefing, before twin snakes actually kicks in, the commander says that:

"The military has been working towards identifying those genes. which are responsible for making effective soldiers" ? as you know it was after the human genome project, so doesn't it mean they want to find out how the next gen special forces has been strengthening themselves via gene therapy and do it themselves?

1. also, this convo is the most evident that our side, do want to enhance the soldier's genes, so why they don't do it on snake?
   snake syas "And so if you knew what genes were responsible for making the perfect soldier, you could implant them in the same way, right?" then the doctor replies "yes, we could" and the commander syas "But it all depends on being able to isolate and identify those soldier genes."

2. so how next gen special forces did enhance their strength via gene therapy? according to the commander they still don't have big boss' remains so...

4.why foxhound needed big boss' remains? if the next gen special forces already enhance themselves via the therapy

timestamp to briefing. - for your convinience.

thanks a lot!