My dd11 has broken her humerus after falling of some monkey bars, 2 years ago she broke her other arm after falling of the ladder of her high bed( back to a normal bed now!) she is in very good health but is very skinny with a extremely slender bone structure, Is this bad luck, her brother is of a more sturdy construction, is equally adventurous and sporty but seems to get away with all manner of scrapes. I don't think for a minute she has brittle bones or anything serious as the hospital would have picked this up, but do certain skeletal types get more fractures. Poor dd facing another six weeks missing swimming and the triathlon she had entered.