Per some internet thing I saw somewhere... and then having just fast forwarded the episode in question to make sure I didn't get one guy'd, Jerry said in Season 6 episode 13 "Evil Ice Dancer" that he slept through Dr. Casoy's lecture. And Dr. Casoy is Alex's father. Also, at some point around 2019, there was a post on youtube by the totally spies channel confirming her last name.