Serena and Venus Williams' half-sister thinks the movie about their father's life and the role he played in guiding the tennis players to superstardom is laughable.

King Richard tells the story of Richard Williams, who is portrayed by two-time Academy Award nominee Will Smith. But according to Sabrina Williams, the film leaves out the first 30 years of Richard's life – when she and her four blood siblings were born and later abandoned.

Richard married Sabrina's late mother, Betty Johnson, in the early 1960s. Together, they had five children: Sabrina, 57, Richard III, 56, Ronner, 55, Reluss, 54, and Reneeka, 49.

Sabrina told The Sun that when she was 8 years old, her dad left to buy her a bike and never came home.

"My sister Reneeka was a baby eight weeks old when my dad left," she said. "How do you leave a baby? I was eight years old, and he left under the pretense 'I'm gonna get you a bike?' I can laugh about it now."

Richard – now 79 and reportedly "incapacitated" after suffering two strokes – went on to marry Serena and Venus's mom, Oracene. He made it his mission to ensure that their two daughters would become tennis professionals, which included writing a 78-page manifesto outlining his blueprint for success.

"He choose [sic] tennis for them, as he knew it could also make him a millionaire," said Sabrina, who claims she's only seen her dad a handful of times since he left her and her four siblings to be "raised in poverty."

"I had two childhoods. The first was OK because we had money, but the second period was very difficult. It was like an instant change," she said, alleging that Richard did not even help her family when her mom was battling cancer in 1998. "If it wasn't for the churches that we belonged to, I don't think my mom would have made it."