[Draft]

I don't think there is a scientific answer for what your asking.

Yeah your mother smoking through out her pregnancy can have effects on your development but judgeing by how tall you are I don't think its a huge factor.

Also I don't believe there is a limit in increasing your enduarance or strength. It might take you longer than others to build up more stamina but your body won't just be like ''Ok, thats it, i'm not going any further'' if you just keep pushing.

You just have to train hard, maybe harder than others but eventually you'll build up more and more.

It would be unrealalistic to say that you can't improve yourself any more.