ingenuous

innocent and straightforward

Roots

-ous / -ious: full of or marked by a quality
gen / gener: birth, kind, origin, or producing

Other words with the gen / gener root

congenial: pleasant, friendly, or naturally suited
disingenuous: not candid; pretending to be sincere
engender: to cause or bring into being
generate: to produce or bring into being
heterogeneous: made of different kinds
homogeneous: of the same kind throughout

Ingenuous honesty feels inborn and unpolished: open because no trick has been added yet.

Her ingenuous question revealed the flaw everyone else was too embarrassed to mention.

Ingenuous can be confusing because it looks like a negative in- word, but that is not the useful memory. Keep the born/native idea: ingenuous speech feels natural, open, and uncalculated. Disingenuous is the opposite: the openness is fake or missing.