If they aren't offspring of the Bollywood elite they're pretty much always ex beauty queens or models (which tho of course is much like female Hollywood stars)
Females: Ash, Sushmita Sen, Priyanka Chopra, Diya Mirza, Celina Jaitley, Bipasha Basu, Ayesha Takia, Lara Dutta, Katrina Kaif, Shilpa Shetty, Frieda Pinto (hmmm dunno if she counts as Bollywood)..
I don't think Sneha Ullal (Ash lookalike) was a model tho..
Males: John Abraham and Dino Morea were models, much more of the Bollywood men compared to the women seem to come from famous families..