Once a Democratic donor, Silicon Valley philanthropist Nicole Shanahan has undergone a dramatic political transition in the few years leading up to her selection as Robert F. Kennedy Jr.’s running mate in the November election. It’s a journey she attributes to the pandemic and her 5-year-old daughter’s autism diagnosis.

Shanahan has come to embrace a doctor guru who believes, wrongly, that vaccines cause widespread injury and that sunshine cures almost everything. Her fringe ideas are now central to a presidential platform that rejects experts and institutions and elevates influencers and entrepreneurs with conspiratorial views and dubious solutions to national problems.