Is it known if the Selmer ranks of quadratic twist families are unbounded? Suppose that $E/K$ is an elliptic curve defined over a number field. For each quadratic extension $F/K$ I can form the twist $E^F$ via the character of $F$. Is there a choice of $E/K$ such that the Selmer ranks $\mathrm{rank} \, \mathrm{Sel}_n(E^F)$ are known to be unbounded?