The relationship between baalei teshuva and their irreligious parents is always interesting. Naively, you'd assume that your kids picking up a set of beliefs which requires them to be respectful to you and try to have a bunch of kids would be seen as a good thing, but...
...this only happens sometimes. There are three psychological reasons people hold beliefs/worldviews. First, an honest belief in objective truth. Second, as heuristics for desired outcomes. Third, maintaining self-perception/avoiding cognitive dissonance/justifying behavior.
In the first case, if your kids pick up a different belief or worldview which you think is objectively false, you might be upset due to a missionary proselytizing mindset, kind of how NPR listeners feel about creationist hicks in Arkansas. It's OFFENSIVE they believe that!
In the second case, you might find the outcomes brought about by your kids adopting frum heuristics undesirable, for reasons of fashion (embarrassing to have a daughter who "covers her hair with a rag" and "breeds like a rabbit"!) or worldview ("think of the carbon footprint!")
In the third, for people with a hedonistic secular worldview ("sex, drugs and rock & roll" or "intellectual exploration"-the latter is a tiny minority like Feynman), frum kids means confronting a worldview in which you are contemptible or, at best, pitiful.
I've seen many examples of people acting very unpleasantly to their children who make teshuva. It seems mostly be driven by the third scenario, a desire to preserve one's image of oneself as a good guy, cool, etc. Usually, malignant Boomerism, same as reverse mortgage to fund...
...hedonic consumption in your old age while the couple of kids you managed to have are drowning financially.