His 21-year-old daughter, Brittany, has given birth to a boy -- Parker Brett. He weighed in at 7 pounds, 7 ounces.
Favre said on his Web site that he and wife Deanna are "very proud" to welcome their first grandchild.
Favre has yet to announce whether he will return to the Minnesota Vikings and play a 20th season in the NFL. Last year the 40-year-old enjoyed one of his best years and helped lead the Vikings to the NFC title game.
The baby's arrival was first reported by the Minneapolis Spokesman-Recorder.
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