A Texas jury was shown a picture of killer FedEx driver Tanner Horner smiling as a young boy — at just about the age of his victim — as the defense brought his drug-addicted mother to the stand.

Horner’s mother, her face blurred, recounted details from his disturbing childhood Wednesday, as he looks to avoid the death penalty for the murder of 7-year-old Athena Strand.

Speaking at her son’s trial in Fort Worth, Texas, Horner’s mother described her own upbringing of abuse and addiction, including being sexually assaulted by her stepfather from the age of 4, and going to rehab at 14 before working in strip clubs as a young woman.

She also said she had been using meth and heroin throughout these years, and tried to kill herself through an intentional overdose before Tanner was born.

Horner’s mother said she was still working at a strip club when she became pregnant, during which she was drinking so heavily that she got “cirrhosis” and continued to smoke cigarettes and marijuana throughout her pregnancy.

She described relapsing onto hard drugs when Horner was around 2, recounting an incident when her young son found her slumped on the toilet strung out on heroin.

“I nodded out one time on the toilet, and I wasn’t using the bathroom or anything, I had just done what I was doing, and I just nodded out, and Tanner came in. He was just a little guy, and he thought I was dead,” Horner’s mother told the defense attorney.

“I’ve never been able to stay sober,” she added.