Nobody is equipped with identical genetics.
I bet those weaker guys at the gym could run a 5k minutes faster than the guys who are genetic freaks in the gym.
That and cultural differences play a role.
Say one guy was raised in a family that never did breakfast lunch and dinner, one guy was raised in a family that sat down for every meal but only light portions, and another guy was raised in a family that ate the biggest meals ever.
Their bodies will all develop very different from one another.
The last guy will probably be years ahead of the other two his first day at the gym.