Genesis Ch 17-24: Young Version Or This Version

As I read through Genesis I try to compare this version of the Bible to the version that we are taught when little. In the one we were taught when little there are some differences for example in the King James Bible they mention that Abraham had a son with the maid that was named Ishmael and then another with Sarah named Isaac. In the version we read when we are young we only know that he had son with Sarah. Also when Lot and his two daughters were in the cave the daughters tried to have sons with him to keep his name alive. They manage to achieve this after they make him drink wine. When two people so close together have sons their sons may have mental or physical disabilities. I sometimes wander if in these cases there are some exceptions or every time someone close has relations the son will have problems?