Identical twin sisters McKenzie and Brittanie say they started using drugs in their early teens. Now 24, McKenzie has been sober for almost four years, but Brittanie admits she is addicted to heroin and has difficulty staying clean after detox and treatment -- and she even lost custody of her young daughter to her mother.

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The sisters claim that their mom, Donna, was frequently absent while they were growing up and that she would go out drinking, come home drunk and not pay attention to them. McKenzie even claims that she smoked pot with her mother.

“You said she failed as a mother,” Dr. Phil says to the young women.

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“I do think there’s failures, absolutely,” McKenzie says.

“The discipline was absent for sure,” Brittanie adds.

In the video above, hear why McKenzie’s fiancé, Chad, claims that Donna is sabotaging Brittanie’s sobriety. What does Donna say? And on Thursday’s episode of Dr. Phil, learn why Chad and McKenzie say they are not inviting Brittanie to their upcoming wedding. Check here to see where you can watch.

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Young Woman Says She’s Caught Between Twin Sister And Fiancé; Dr. Phil Tells Her Why It’s Not A Choice