Big bones are actually a lie. When a person's bones were actually bigger the person would also be taller. Bone density however can be greater than average, professional lifters have a much greater bone density as otherwise they wouldn't be able to lift this heavy.
The world famous Joseph Merrick, better known as the Elephant man (https://en.wikipedia.org/wiki/Joseph_Merrick) most likely suffered from https://en.wikipedia.org/wiki/Proteus_syndrome which can actually cause abnormal bone growth.
People with obesity and overweight run (no pun) a greater risk of bone weakness however due to bad nutrition and lack of vitamin, and distorted metabolism.