Washington — The National Zoo's panda parents, Mei Xiang and Tian Tian, have another son.

The zoo announced Friday morning that the surviving panda cub is male and the son of the zoo's male panda Tian Tian.

Mei Xiang gave birth to twins Saturday, but the smaller cub died Wednesday. Officials say that smaller cub was also a male fathered by Tian Tian.

The cub's cause of death hasn't been determined. Keepers say the larger cub is doing well and growing.

Tian Tian is the father of Mei Xiang's other cubs, daughter Bao Bao and son Tai Shan. During this year's panda breeding, Mei Xiang was artificially inseminated with semen from Tian Tian and a panda in China that was deemed a good genetic match.