Honey Boo Boo's teenage sister has a baby with three thumbs, feeds it Mountain Dew

They say reality TV is always scripted, but…

The teenage sister of beauty pageant star Alana "Honey Boo Boo Child" Thompson has welcomed a baby daughter with three thumbs.

18-year-old Anna "Chickadee" Thompson gave birth to baby Kaitlyn last month, and photos taken at the Sparkle and Shine beauty pageant this weekend reveal the reality bub has an extra thumb on her right hand.

New grandmother June "Mama" Shannon, 33, hit back at reports she mocked her granddaughter's abnormality. "We have embraced [the third thumb]. It makes Kaitlyn more special to us," she told People Magazine.

Adding to the controversy, 12-year-old Lauryn "Pumpkin" Thompson was spotted dipping baby Kaitlyn's dummy in a can of Mountain Dew and passing it to her niece to suckle while the family watched Alana compete in the pageant.

Teenage mum "Chickadee" realises 12-year-old "Pumpkin" has fed her baby Mountain Dew.

Six-year-old Alana shot to fame after her spirited appearance on the reality TV show Toddlers & Tiaras earlier this year. Her 'Mama' came under fire at the time for feeding her "Go-Go Juice" — a concoction of Red Bull and Mountain Dew — to stay pepped up during pageants.

Alana and her family now star in the spin-off reality show Here Comes Honey Boo Boo.

Here's a couple of clips from the show, which is yet to air in Australia: