well I was born 6 weeks early, got into an accelerated KS2 class, won a scholarship, duxed my year and took final exams with a score in the top 5%. If this study is to be believed I would have been rivalling Stephen Hawking if I'd stayed put another 6 weeks.
Oh by the way, my full-term brother 3 years younger was not in the slightest academic and left school for an apprenticeship at 15.