Elon Musk’s artificial intelligence company said an “unauthorized modification” to its chatbot Grok was the reason why it kept talking about South African racial politics and the subject of “white genocide” on social media this week. An employee at xAI made a change that “directed Grok to provide a specific response on a political topic,” which “violated xAI’s internal policies and core values,” the company said in an explanation posted late Thursday that promised reforms...