You want an example, my own beliefs have been in place about same sex marriage and homosexuality for at least 18 years now, since I was in my mid-teens and old enough to even realize that homosexuals were treated differently for who they loved.
And that is still social engineering. Just because a group got its way and has maintained it for some time does not mean that it is not maintained via social engineering. The main way it is done in connection with same sex relationships/homosexuality opposition is through religions. Slowly though younger generations are rethinking their beliefs and accepting that perhaps those who taught them those things were wrong.