Question

Do all $\mathcal{N}=2$ Gauge Theories “Descend” from String Theory?

Answer 1

Thermodynamic Bethe Ansatz (TBA)-like equation derived by Nekrasov and Shatashvili (NS) for N=2 4d Super Yang-Mills (SYM) theories. In this regime of the background, -- we shall show --, the instanton partition function is characterised by the solution of a TQ-equation. 

Answer 2

Thus string theory is a theory of quantum gravity. String theory is a broad and varied subject that attempts to address a number of deep questions of fundamental physics. ... It later developed intosuperstring theory, which posits a connection called supersymmetry between bosons and the class of particles called fermions.