When I was a kid, one of my mates only had 1.5 legs.
It was astounding what he could do, On the army assalt course he was better than any person on two legs (as he could land on top edge of a wall on his shin)
The only thing he could not do was run as fast as a normal kid, and he had a tendancy to fall of his bike on one side, otherwise it made zero difference to him or anyone else. He used to go through legs at the rate of two a year, so was often on crutches whilst his leg was being repaired for crash damage