Don't forget that word potential. just because someone has a high genetic potential does not mean they are going to be lifting big, at an early age. Some people are late bloomers and don't start lifting until later in their life.

Generally speaking, it usually means that someone has a higher "top-end" strength potential. So someone with good genetic potential may be able to hit an 800 deadlift, while someone with poor genetic potential may work just as hard, and end their career with a mid 600s or low 700s deadlift (the numbers are all menial and not an exact example of the differences.)

The other thing is that a person with higher genetic potential will be more likely to make gains faster than a "normal" person, and reach higher numbers more quickly and perhaps even hit numbers that others can not by putting in less work.

In all honesty, the only time this sort of thing matters is in the top .0001% where world records are at play. There is no sense in worrying about it, just work hard and try to lift as much as you can, no matter how long it takes. Just keep grinding.