The group of young adults coming up now are not concerned about age, sex, etc of their partners. They have been raised in an atmosphere of if you want it you should have it. We are reaping what has been sewn.
sewn: past participle of "to sew" ("to fasten by sewing").
sown: past participle of "to sow" ("to plant seeds").
Thus, your sentence should have read:
We are reaping what has been sown.
You're welcome!
Regards,