Family therapist Moses, 36, accused their mother Mia Farrow of turning them against their father, as pay back for Woody marrying another of Mia's adopted daughters, Soon-Yi Farrow Previn.
"Of course Woody did not molest my sister," Moses told PEOPLE. "She loved him and looked forward to seeing him when he would visit."
Woody holding Dylan and Mia carrying Ronan
While Mia and Woody never married, they adopted Dylan and Moses and had one biological child, Satchel Farrow – also known as Ronan – together. The couple lived in separate homes.
"Dylan never hid from him until our mother succeeded in creating the atmosphere of fear and hate towards him," added Moses.
Just last week, Dylan, now married and living in Florida under a different name, published an open letter in which she described how she was molested at the age of seven – an accusation Woody has always denied.
"The day in question, there were six or seven of us in the house," said Moses. "We were all in public rooms and no one, not my father or sister, was off in any private spaces. My mother was conveniently out shopping.
"I don't know if my sister really believes she was molested or is trying to please her mother. Pleasing my mother was very powerful motivation because to be on her wrong side was horrible.
"My mother drummed it into me to hate my father for tearing apart the family and sexually molesting my sister. And I hated him for her for years. I see now that this was a vengeful way to pay him back for falling in love with Soon-Yi."
Woody and Soon-Yi Farrow Previn
Dylan has responded to her brother's comments, insisting that she is telling the truth.
"This is such a betrayal to me and my whole family," she told PEOPLE. "My mother never coached me. She never planted false memories in my brain. My memories are mine."
Mia and Ronan have expressed their support for Dylan by taking to Twitter.
"I love my daughter. I will always protect her. A lot of ugliness is going to be aimed at me. But this is not about me, it's about her truth," wrote Mia.
Ronan followed suit, posting, "I love and support my sister and I think her words speak for themselves."
Woody was denied visitation rights with Dylan
At the time of the allegations, Woody was taken to court and accused of "inappropriately touching" Dylan. The claims were investigated and Connecticut state attorney Frank S. Maco announced that while he found "probable cause" to prosecute Woody, he decided to drop the case because the seven-year-old was too "fragile" to withstand a trial.
Mia, who Frank claimed agreed with him on dropping the charges, won custody of the children in 1993 and denied Woody visitation rights with Dylan.
Woody and Soon-Yi married in 1997 and have two adopted daughters together.