In case I didn’t explain myself well enough here goes. Although a person’s choice is in his own hands and we won’t necessarily point to his parents as the reason for his choices, there are still things within his behavior that we can trace back to his upbringing. When people go OTD and reflect back on their life they will describe some positive experiences along with the negative ones, to which they might attribute their general negative outlook on Judaism.
This Miriam Bas Bilga, who kicked the Mizbei’ach when she came there with her husband (a Greek sergeant) during the pillage of the Mikdash, referred to the Mizbei’ach as a wolf swallowing the money of the Jews. Even if she went off this would not have been her outlook. Why would it cross the mind of a former Jew to hate the Mizbei’ach? This is why the Rabbis concluded that there was obviously somewhat of a negative attitude that she picked up in her father’s house. As religious Jews, they obviously didn’t call the Mizbei’ach a wolf, but they might have been theorizing how they can save money from being wasted. Such as, “It’s a Shud to always bring a cow, they could bring a small sheep; there’s no Chiyuv to bring that many; if they work one minute slower they can save 25 Kikkar a year.”