Wasn't the relationship between Candide and Cunegonde incest?

No,and
Cunegonde's relationship would not have been considered incestuous at the time. For one thing,
sexual relations between cousins were considered perfectly acceptable in those days. Also, one
should bear in mind that Cunegonde is an aristocrat, a baron's daughter no less, and for the
upper classes marrying one's relations was not just permitted, but actively encouraged, as it
ensured the continuance of the family line.

The aristocratic gene pool was,
by its very nature, rather shallow, and so it was often virtually impossible to avoid marrying
someone to whom you were related. In a later generation, Queen Victoria married Prince Albert,
her first cousin, by whom she sired no fewer than nine children.

, like the
good philosophe he is, appears to be criticizing the unthinking
subscription to tradition, a common refrain of Enlightenment thinkers. There's certainly no
other explanation as to why Candide would want to marry someone as vacuous, boring, and shallow
as Cunegonde.