The Truth Is Out There... and It Hurts - S1-E8
Question: How come in this episode when Andy asks Pru if her kids will inherit powers she says "If they're girls, they will"? Why will only the girls inherit their powers? We know this is not true, both Wyatt and Chris have powers, Wyatt has them even before he is born.
Answer: The "only female witches" rule only applied to the Warren line, Wyatt and Chris got their powers as they were the first males to be born from a witch and a white lighter, that changed history completely since it was forbidden for witches and white lighters to have intimacy before Piper and Leo Prue was not wrong.
Answer: Honestly that was Pru when she was inexperienced in the craft. she didn't understand that men could be witches too because "Grams" made her believe so. In the the episode 'Secrets and Guys' the sisters discover that "Grams" was wrong and that men could be witches too. Later in the series the sisters even acknowledge this fact and use the term male witch throughout, eg. the season three episode titled 'Blinded by the Whitelighter' when Phoebe has a premonition of a male witch being attacked by the evil warlock Ames, played by S. Valentine.