Google co-founder Sergey Brin started a personal blog Thursday, beginning with the revelation that he has a genetic predisposition to Parkinson’s, the nasty incurable disease that has crippled Michael Fox, the actor. Brin’s mother’s got it and so has her aunt but cases of familial Parkinson’s are quite rare, Brin says, confessing that he never bought the idea that it was hereditary. But his wife’s involved in 23andMe, the genetic testing start-up that Brin put some money in, and it was 23andMe that discovered that Brin, 35, carries a mutated LRRK2 gene known as G20195, a Parkinson’s flag. Why Brin chose to share this information is anybody’s guess – a plea for sympathy, an advertisement for 23andMe? The industry, particularly Wall Street, is still absorbing Steve Jobs’ anorexic appearance. See http://too.blogspot.com/.