The parents had originally faced a total of 82 charges but 60 of those were dropped towards the end of the trial after legal issues arose.
Some readers may find the contents of this article disturbing.
The jury acquitted the father on nine charges of sexual assault and acquitted the mother of sexual assault.
The offences occurred between 2009 and 2011. They had both denied all the charges.
His father had alleged he was brainwashed by social workers. He is appealing his conviction.
The 66-year-old man was born in the UK to Irish parents.
He moved to Ireland and met the boy's mother who is 38.
She had previously been married to an abusive partner and all four of her children had been taken into care.
Two years after meeting, the couple had a child - the boy at the centre of this case.
Lawyers for the father said he came before the court "largely of good character" with a few previous convictions for theft, but none for violent or sexual crime.
Senior Counsel Colman Cody said the man had a stable work record and had done voluntary work in the past.
He urged the judge not to impose the maximum sentence of life, saying it was only appropriate in cases of particular depravity.
They said there was objective evidence during the trial that the child had enjoyed some happy times with his father and had been well cared for and regularly taken to the doctor.
They said it was "not a case of unrelenting darkness" - it was "not the house of horrors portrayed by the prosecution".
Lawyers for the mother said when she was aged seven and living in the UK, her own mother's boyfriend started to sexually abuse her.
She became pregnant by him when she was 14 and the child was taken into care.
She then married this man when she was 17 and he brought her to Ireland where they had two further children who were also taken into care.
In 1999, the marriage ended when she said there had been continuing physical and sexual abuse by him.
She met another man with whom she had a child. That child was also taken into care.
In 2001, she met her current partner and co-accused and became pregnant with the boy at the centre of this case.
The court was told she has a mild cognitive disability and had attended special schools growing up.
A psychological report said she was dependent on the boy's father and would have been unable to protect the child from him.
She remained in regular contact with him after their conviction through letters and phone calls.
Defence counsel John O'Kelly asked for non-custodial sentence.
He said his client "never had a chance from the age of seven" and "has had hardly any breaks in life except for the very worst kind that can occur".