Megan Fox's toe thumb became an internet hit at the time when the action Sci-Fi movie 'Transformers (2): Revenge of the Fallen' was released (see picture below) - her thumb condition was not noticed at the time of her first appearance in the 2007 'Transformers' movie.
Back then hand surgeons have described that even though genetic factors are involved in this (often inherited) inborn club thumb condition, Megan's thumb abnormality can be recognized as just a minor cosmetic imperfection.
According medical science brachydactyly type d (BDD) concerns a minor physical anomaly.
On december 17, 2012 at The Tonight Show with Jay Leno Megan Fox unveiled her own (non-scientific) 'thumb-theory' for how she acquired her thumbs; Megan described that her mom had been eating Tuna everyday while being pregnant of Megan - tuna is known for high levels of Mercury.
Other actors/models who have a club thumb include: Malin Akerman (US actress), Tory Mussett (Australian actress), Ashley Lynn Cafagna (US actress), and Kristen van Der Noot (Germany DJ and model); the Russian author and Nobel laureate Alexander Solzhenitsyn is also a well-known person who had at least one clubbed thumb.