Teen Mom’s Catelynn Lowell has been mum since she recently made the big decision to take legal custody of her teenage sister, Sarah Haviland.

Now In Touch can reveal the reason for the drastic move: Catelynn and Sarah’s troubled mom, April Baltierra, had kicked the 16-year-old out of the house.

“She was living on a drug addict’s porch without any food — what else was I supposed to do?” Catelynn tells In Touch, on stands now.

Four years after putting their baby girl, Carly, up for adoption, she and fiancé Tyler Baltierra, both 21, are learning how to parent for the first time. “We’re not raising her, but guiding her,” Catelynn adds.

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