Hi! A part of plot of the upcoming season 25 episode, "What to Expect When Bart's Expecting?" says:
"But when his spell makes her pregnant instead, he becomes a savior to Springfield couples trying to conceive."
Bart would be Art teacher's son's dad? Bart can't have sons, because is a 10 years old boy. Unless in future-themed episodes like "Holidays of Future Passed" and "Days of Future Future", where Bart is a 40 years old adult.
I hope answer!. The episode will premiere this sunday.