This is the reason that the show ended on a serious and controversial note.
The five-year-old little girl who plays Charlie, Mia Talerico, has recently had some very violent sounding death threats. It is believed that the cause of these death threats is a recent episode of the show that featured a lesbian couple.
The death threats included the phrases “Die Mia, F***ing Die in hell! Kill yourself, you deserve to die.” followed by “Yes, kill yourself [SIC] stupid b*t*h.”
They are taking these death threats seriously and have thus chosen to cancel the show. The last episode took place in February 2015…one last Duncan family dinner together.