During her time with the family, the numbers whizz recalled cooking with her step dad and sneaking out to parties late at night.
The visibly emotional star also spoke about the time she had to leave when her mum and Gabriel split up after ten years together.
“You know I loved him. To me, he was my dad,” she said to her step brother.
“He thought a lot of you too, he always used to say, ‘My Cazza’,” Arthur recalled.
“I missed him. When mum left that final time, she said I wasn’t allowed to come back, and so I didn’t, cause that’s what she said. And that hurt, ‘cause I missed him.”
Closer to Home continues next Tuesday at 8.30pm on BBC Wales.