Speaking from the family home in Mablethorpe, Lincolnshire, he said: "I know my son and we have always just assumed he was bisexual, as it turns out he is gay. It's just the way he was, even when he was younger.
"It was his general mannerisms. A parent knows their child. I don't know why he has waited to come out with all this. His whole life has been a lie.
"He has told me in the past that he admitted that he started experimenting with a lad when he was younger."
Scott's stepmother Gail, 56, who met Scott's father when Scott was 4, added: "We've asked him for years if he likes men and he could have just admitted it to us."
She added that Scott had slept with at least one man when he was 17 and said that the painkillers had not altered his sexuality.
'I think my painkillers turned me gay''I never had any desires for men, I didn't look at men as if 'I really want you' before', Scott Purdy tells us.
So can painkillers turn you gay? Dr Ranj says 'I'm going to say no. But think it's great that Scott is happy...'
Posted by This Morning on Wednesday, 18 April 2018
Scott had claimed that the medication caused him to dump his girlfriend of six-months because he "craved male attention" and lost his sexual attraction to women.
He said that Sarah understood when he told her that he was no longer attracted to women.
But his parents expressed sympathy for her and said the whole episode could have been avoided if he had spoken to them before he had met her.
Pregabalin or Lyrica is a medication used to treat epilepsy, pain associated with the brain, and generalized anxiety disorder. Side effects include loss of libido and mood swings.
But in an ironic twist his father said that he had been prescribed the same painkillers to act as a muscle relaxant to help him sleep following cancer treatment.
Purdy, who has another son Damian, 22, said: "I take them, they are not a painkiller, they are a muscle relaxant. They prescribed them for me after I had cancer to help me sleep. I have been on them for quite some while and I'm still straight.
"I saw that doctor on This Morning yesterday, how he managed to keep a straight face I don't know."
Scott, from Louth, Lincolnshire, went on ITV's This Morning to warn viewers about taking the drug.
He said: "I noticed my libido for women had gone and I was wanting male attention.
"I was with a girlfriend I had been with for around six months.
"I had never been interested in men. When I was younger I was a little bit curious, but a couple of weeks after I started taking it I turned around and said I didn't find her physically attractive anymore. She knew I was taking Pregabalin.
"I said to her, 'I don't really know what's happening to me and I told her I like men and I just can't be with you'."
Lyrica is manufactured by Pfizer - the pharmaceutical giant which also makes Viagra used to treat sexual dysfunction in men.
A spokesman for Pfizer said: "When prescribed and administered appropriately as per the approved label, Lyrica® (pregabalin) is an important and effective treatment option for many people living with chronic neuropathic pain, generalised anxiety disorder and epilepsy.
"The clinical effectiveness of this medicine has been demonstrated in a large number of robust clinical trials among thousands of patients living with these conditions.
"To date, the worldwide exposure to pregabalin is an estimated 34 million patient years.
"If you are taking a medicine and experience any unexpected side effects, we recommend that you immediately report these to your doctor or to another healthcare professional, such as a nurse or carer.
"Patient safety is, and will always be, Pfizer's utmost priority."
