It's All in the Releve
Many young dancers do not realize how high the releve needs to be. Stretch the foot and build it's mobility so you can fully extend that arch AND keep your knee straight! This is a gradual build that happens by applying your technique at the barre as you advance. Yes, some people are born with "those feet" - but even those who are not- can achieve a beautiful releve! In fact those with beautiful feet often have to work even more to have the strength to support that flexibility.
Source: Ballet Foundation