Alternatively, I still think Tyrion would be a Tywin clone, reliant on leading an army from the back as opposed to leading the frontline charge. Tywin was never particularly idolised for his sword-abilities, but he is the ultimate tactician, in war and peace. I'd like to think Tyrion would be just as cunning if he'd been born a taller man and that Tywin would've respected him for it. Tywin would have less contempt for a man made in his own image, and there are even times in the series that Tywin seems to recognise Tyrion's prowess ahead of his other children, despite never admitting it.