Disneyland may be called the happiest place on Earth, but just a short drive away, at a California court, the entertainment tycoon's fortune is the centre of a four-year, US$400 million (NZ$490m) family feud.
Walt Disney's youngest daughter, Sharon Disney Lund, who died in 1993, left a massive trust fund to her children, Michelle Lund and Brad Lund. The twins were to be given lump payments from the estate at their 35th, 40th and 45th birthdays.
At each of those milestones they were to be given a 20 per cent slice of whatever was in their trust.
But the 43-year-old twins have not spoken since 2009 when the trustees stopped making Brad's payments after Michelle claimed he had Down syndrome, the Daily Mail reported.
According to the terms of Sharon's will, trustees were instructed to withhold payment if either of the children had not "demonstrated the maturity and financial ability to manage and utilise such funds in a prudent and reasonable manner".
Brad was told that he did not meet the standard while his sister did, and she has received her payments. Brad is backed by the twins' father, Bill Lund, who married Sharon Disney in 1968 and helped build Walt Disney World in Florida. The couple divorced in 1977.
Now aged 79, Lund has said the feud has torn the family apart.
In 2009 Michelle had a brain aneurysm which Brad said left her with brain damage. However, the trustees decided she could have her 40th birthday payment because she was "98 per cent back to normal", the Sydney Morning Herald reported.
In a petition to the court, Brad is accusing the trustees of a breach of trust, demanding payment of his birthday lump sums, the removal of the trustees, and punitive damages against them.
Members on his side of the argument have said he is "modest in his spending" and "lives well below his means", as opposed to his sister who has bought "numerous multimillion-dollar homes" and throws lavish parties.
But the trustees have suggested Brad is not able to manage his inheritance owing to a "chronic cognitive disability" and lack of maturity.
Neither twin has been diagnosed with the conditions described.
In 2002 the twins' childless half-sister, Victoria, died. According to Brad, her 35th birthday distribution was made "even though she was abusing drugs and alcohol" and the trustees had "questions regarding her maturity". Following her death, what remained in her trust is believed to have been added to the hundreds of millions of dollars in the twins' trusts.
The case started on Thursday and is expected to last three weeks.