your mom <--------------------- This was posted by a douche bag.
Logan was born James Howlett quite a while ago (end of either the 18th or 19th century - I forget which). He was a very frail and sickly boy. The product of his mother's affair with the groundskeeper, he was raised as the legitimate child. This, like just about everything else in his life, ended badly.
Despite what the (really bad) movie declared, their has of yet been no canon confirmation that he and Sabretooth are brothers.