LaShirley Morris, 27, and her sister, Glenndria Morris, 25, from Atlanta city in Georgia have been charged with the killing of Kejuan "King" Mason on October 21 last year, Fox 5 TV channel reported.
Kejuan's family said they were initially told that the child choked on a cupcake but probe authorities had ruled that the child died of blunt force trauma.
"They (the sisters) were mad at the young boy for taking a cupcake from the kitchen," the police said.
Kejuan and his twin brother Kerry moved in with Glenndria after their parents lost their custody.
The toddler's mother said she had lost custody of the boys when she did not have a place to live but was working to get them back.
If convicted, the sisters could face life in prison, the report said.
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